DiskZIP Review - Finished!

Discussion in 'Windows OS and Software' started by msintle, Apr 11, 2018.

  1. msintle

    msintle Notebook Consultant

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    3. In Use - DiskZIP Offline

    Let's boot DiskZIP Offline from the Start Menu:


    The user interface again embodies the minimalist design ethos of DiskZIP. The software settings and progress feedback are all rolled into one:


    Maybe a bit too minimalist here, as an options window is available for DiskZIP Offline, accessed from the almost-hidden chevron found on the right of the big box that is the "Compress" button:


    This menu allows us, among other things, to take a peek at the advanced options which are available specifically for DiskZIP Offline. Let's succumb to our curiosity again, and look here first:


    This seems to spill the guts of DiskZIP Offline out in the open. I say so, because the biggest section of the dialog is off-limits, unless you are being directed by DiskZIP Technical Support. I am not that, so I will not speculate on these settings here at all. However, there's some user configurable settings here still.

    Automatically compress new files: This seems to enable NTFS compression, buying you more time until you have to recompress your disk because you've added so many new apps and files since your last compression pass with DiskZIP Offline that it has become full again. Not worth it in my opinion, I agree with DiskZIP's official recommendation to avoid it here, but I could see it coming in handy on chronically full drives.

    Compression boost: This slider is a bit counter-intuitive, perhaps DiskZIP have erred on the side of oversimplification here. It's actually a slider moving across three settings here, instead of two. The left-most setting is a pass-through, where the slider has no effect at all and the compression boost is turned off. The second left, which is what I have portrayed above, is the fastest (and weakest) compression boost. The right most setting, is the strongest (and slowest) compression boost.

    Note that the compression boost is just that - a boost to the main setting found in the main user interface. It doesn't seem to make a noticeable difference in my anecdotal experience.

    There's also more settings and features accessible on the Chevron menu.


    Excluded Folders: Shows a dialog where you can exclude one or more folders from compression with DiskZIP Offline. It is vital to exclude folders containing frequently updated files, because compressing them with DiskZIP Offline takes time, and then they are automatically going to be uncompressed the first time they're updated anyways. Some folders may also need to be excluded for proper operation of the operating system, so DiskZIP Offline already comes with a list of built-in default exclusions.

    Be sure to not delete any of the default exclusions here, unless you know what you are doing!

    Feel free to add and delete your own folders though.

    Clone: Here's the disk imaging feature of DiskZIP Offline. This menu contains two submenus, Backup and Restore. First click Backup to compress your disk onto an external drive, which you can then carry to a new computer where you've previously installed DiskZIP Offline. Next, you click Restore on that new computer, and then choose Restore Compressed or Restore Uncompressed. Restoring uncompressed clones your current operating system to the target PC in uncompressed form, even if the original OS itself is in a compressed state. Similarly, restoring compressed clones your current operating system to the target PC in compressed form, even if the original OS is uncompressed. Once you've done a compressed restore, it is as good as having compressed the target PC with DiskZIP Offline - you get all the benefits, including more disk space and faster performance.

    Backing up your disk is a great way to get your feet wet with DiskZIP Offline. It's a great way to get a feel for how DiskZIP Offline works. There's absolutely no risk to your PC, since no changes to it are made during the backup. It was one of the first things I tried to get a sense for how much free disk space I would gain by running DiskZIP Offline, since there's no way to know that without trying. The final size of the DiskZIP.WIM file on your backup disk gives you an indication of how much space it takes to store all your apps and files in compressed form, and you can expect your actual disk usage to be roughly the same (with a gig or two extra added on top for good measure, plus of course any space consumed by excluded folders).

    Once you've compressed your disk, you can go back and uncompress your disk any time with DiskZIP Offline. Just point at this menu, and choose either From Backup Disk, or Use Latest State. It is faster to just uncompress from a backup disk, as this option, for all practical intents and purposes, just clones the image on your backup disk to your PC in uncompressed form. But if you're like most people, you actually want to uncompress the current state of your disk, not how it was some days (or weeks or months or even years ago), so you'll want to uncompress using the latest state. This is understandably slower, as it actually compresses your disk again to a backup disk, and then applies that freshly compressed disk image back onto your disk in uncompressed form. Of course, you can speed up uncompression by choosing the MaxSpeed compression grade (which, sure enough, is counter-intuitive when you're trying to uncompress your disk - but that's how DiskZIP Offline works).

    The only real inconvenience with uncompression is that you'll need an external backup disk to get it to work, and this external backup disk must have enough free disk space to hold your compressed disk image file. Feel free to check the size of C:\DiskZIP.WIM as this will give you an idea of how large, roughly, your external backup disk needs to be. If you have an internal disk (or a second internal partition) big enough to hold a file of this size, you can just choose that partition as your "Backup Disk", and get the job done without any external media at all, which can certainly come in very handy.

    Of course, it should go without saying that you should not try to uncompress your disk unless your disk already has enough free disk space to hold all of your compressed data in uncompressed form. Unfortunately, DiskZIP Offline does not seem to validate this free disk space requirement in my experience. Maybe there's something odd in my setup, but I've tried this on many virtual and physical machines, so I doubt it. You will simply need to ensure that you have enough free disk space before proceeding with uncompression. At least, if anything goes wrong, you can just restore your disk using DiskZIP Offline in clone mode, using the backup disk that is updated during the uncompression process. Your data is always safe.

    System Refresh: This is one of my favorite features in DiskZIP Offline! It is a very, very nice thing that you get thanks to the technology based on a compressed disk image file, instead of per-file compression.

    System Refresh is essentially a free "undo" to recover from any intentional or unintentional changes you may have made to your system since your last compression pass. For example, you may have installed some software which broke your business critical software configuration. Instead of spending harrowing days figuring out what broke and how to fix it, just choose System Refresh!

    Or, you may have been outright the victim of a malicious attack, getting infected by some kind of malware, spyware, ransomware, or any good ole' PC virus. The good news here is that your compressed disk image file is absolutely impregnable to malware. While this doesn't mean your PC is completely protected (after all, DiskZIP Offline is not an anti-virus solution), it does mean that you're just a single click away from restoring your PC to the same state it was in when you had last compressed it.

    I should clarify here, of course, that when I say restore your PC, what I really mean is restore your DiskZIP Offline compressed partition. DiskZIP Offline's protection applies only to the partition you compress with it, not to the entire PC magically somehow.

    So let's say you got infected by some kind of ransomware that starts merrily encrypting your files and demanding ransom. This malware will have no idea that your data is safe inside the compressed disk image file, which it will never be able to access or encrypt. Just click System Refresh, and you've saved yourself from that ransomware, without paying a dime. All of the files encrypted by the ransomware, and the ransomware itself, will be nuked out of your disk.

    There is also a not immediately obvious, but very practical use of the System Refresh function. Its essentially another type of backup/clone operation, but one you do yourself directly, instead of choosing the built-in options in the DiskZIP Offline software. The workflow goes as follows.

    1) You normally compress your disk with DiskZIP Offline, at any time when you want to take a "snapshot" of its current state and back it up.

    2) You use Windows File Explorer, the command line, your favorite file management tool, or basically whatever you use to manage files, and you copy your compressed disk image file to a backup disk, be that external, internal, networked, or wherever. You can even keep multiple compressed disk images files to ensure you have depth in your backup strategy and multiple dates to go back to in case of need. There's absolutely nothing magical about a compressed disk image file at all, its just a really, really large file that happens to contain everything on your disk, including both the operating system and apps, as well as your own files and data.

    3) Copy whichever backup file you want to clone to the root drive of the target PC, which should already have DiskZIP installed.

    4) Choose System Refresh, and you've got yourself a manual clone!

    We've got only two options left to cover before we get to the main software operation:

    Reload Drive List: DiskZIP Offline always seems to automatically detect when you attach an external drive and updates the drive lists instantly, so I'm not sure why this option is here explicitly, to be frank.

    Command Line: Launches a command line window. While this doesn't add any value when Windows is already running, it can and does come in handy when DiskZIP Offline is actually processing your disk offline, and you don't have any other way to launch a console window to take a peek around what's going on, while it's going on. In fact, while processing a disk, all menu items get disabled except this one, so clearly this is intended to be used while a disk is being processed. I frequently launch Task Manager by running "taskmgr" from this console window to see how much DiskZIP Offline stresses my PCs while running on them. You should not expect to be able to run your email client or web browser from this command line window, but most simple Windows apps work.

    Now that we've discussed all the available options, we're finally ready to explore the main user interface, which is surprisingly simple and streamlined.
    Last edited: Apr 16, 2018
  2. msintle

    msintle Notebook Consultant

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    3. In Use - DiskZIP Offline (Continued)

    Here we are. If you skipped the previous sections, don't worry - you're at the right place! The below is all you really need to know to make the best of the entire DiskZIP software collection, in my opinion. Please don't even worry about all the options I have described above, possibly in much greater detail than is necessary.


    It's extremely simple to compress your disk.

    First, choose the disk to process. Drive C: will be selected for you automatically. Leave it at that.

    Next, do you have a backup disk, ideally as large as Drive C: itself, but maybe up to half the size if you're feeling adventurous? If so, check the "Optional Backup Disk" box, and select the drive letter for the disk here. If not, leave it unchecked.

    Then, select the type of disk you have. Just click on the connector type. Don't know what this is? Choose MaxSpeed if you want the quickest processing and least free disk space available. Choose MaxSpace if you want the most free disk space available, with a delay in processing. Or choose something in between.

    Finally, click the big Compress button, and get ready to reboot your PC! That's all there is to it. Here is what you will see after rebooting:

    Windows 10 Fall Creators x64 UEFI-2018-04-16-16-10-34.png

    Choose DiskZIP Offline on this menu. DiskZIP Offline will not compress your disk (or make any changes to your system) until you select this menu item.

    This rebooting is magical, and definitely merits a few extra words. It is one of the things that really inspired confidence in me while using DiskZIP Offline. It just works. Even on RAID systems with custom drivers. It just works. This is magical. You don't need to create a USB drive with a bootable version of Windows and then add some drivers to it and then figure out how to get it to work with UEFI systems, or BIOS systems, or both. It just works. No external disks are required, which I find to be convenient to the extreme. If I regularly had external drives lying around matching the size of my main storage, I probably wouldn't be trying DiskZIP anyways! Therefore it is vital that this all works in a single click, without fuss, for all users, without spare disks lying around. It does.

    Windows 10 Fall Creators x64 UEFI-2018-04-16-16-11-29.png

    Shortly after your selection, DiskZIP Offline stars an instance of Windows PE, from where it accesses your main boot partition to process all of the files it contains, even those that would be typically locked by Windows or other apps on your PC. It first checks your disk for errors. If you chose a backup disk, it is scanned as well. DiskZIP Offline will not run unless your selected disks are in perfect condition, to eliminate the chance of unintended data loss.

    Windows 10 Fall Creators x64 UEFI-2018-04-16-16-14-50.png

    DiskZIP Offline then reads your disk and compresses it, bit by bit, until its done. Finally, DiskZIP Offline invokes DiskZIP Online directly, without you having to do anything, to optimize the newly compressed disk. You don't have to babysit the process at any point past choosing DiskZIP Offline from the boot menu in any way. Just walk away.

    When you return, your PC has already booted back into your main Windows installation without any further fanfare. Everything is where you left it, pixel-perfect. Your PC is faster and has more disk space. You've made it. Enjoy!

    What Is The Risk Of Data Loss?

    I want to be very clear about this, since so many readers have expressed concern with the potential of data loss. If any of the following happens, you might lose data:

    1) You lose power (or your battery runs out) during compression. If you haven't selected a Backup Disk, your system may become unbootable, and you may lose your apps and files, and you may need to reinstall Windows.

    If you selected a Backup Disk, the worst that can happen to you is you need to reinstall Windows, and then restore from your Backup Disk. All your apps and files are safe on the Backup Disk, because DiskZIP Offline does not even touch your boot partition until everything is squared away securely on your Backup Disk.

    2) There is a media error on a disk
    . Your system may become unbootable, and you may lose your apps and files. You probably don't want to reinstall Windows until you've gotten a working disk.

    If you selected a Backup Disk but it has hardware faults also, the Backup Disk cannot protect you.

    3) A software bug occurs. Yes, it is true that nobody can rule this out. And there's no telling if the software bug might wreck your Backup Disk and your boot partition both at the same time. I've never run into a fatal software bug with DiskZIP Offline in my two years of using it, so I cannot speculate. Quirks, yes, but nothing where the software does not work as documented.

    You must always approach all imaging tools with a level of caution, be they DiskZIP Offline or a third party partition manager (even Windows's built-in Disk Management). Whatever precautions you take before using a disk partitioning tool, I'd take the exact same precautions with DiskZIP Offline. Nothing more, nothing less.

    What Is The Risk Of Data Loss After Having Compressed My Disk With DiskZIP Offline?

    I find this to be a very legitimate question, so I definitely want to address it in some detail.

    I find the risk of data loss after you've successfully completed a compression pass with DiskZIP Offline to be nearly identical to the risk of data loss you ordinarily are at while running Windows without transparent disk compression.

    Actually, it may help clarify things to refer to what DiskZIP Offline does as not transparent disk compression, but transparent disk uncompression!

    This is actually what is really going on when you use your PC after having compressed it with DiskZIP Offline. There is no transparent compression going on in the background or foreground or anywhere (at least, not unless you enabled NTFS compression, which is disabled by default in the settings we covered earlier).

    There is transparent disk uncompression going on all the time though, as what appears to be your good ole' disk is now actually just a single file, C:\DiskZIP.WIM, which contains virtually all of the files and folders and apps and settings and data and media on your disk (except, excluded folders of course).

    So what's the risk with transparent disk uncompression? Sure, you can still lose data - especially if the disk you're using develops bad sectors and C:\DiskZIP.WIM happens to occupy some of those bad sectors.

    Which is exactly why I say the risk is nearly identical to when you're running Windows itself without disk compression: If the disk you're running Windows on has bad sectors, you may lose data that resides on those bad sectors; with or without transparent disk uncompression!

    Taking this a step further - what if the critical metadata for C:\DiskZIP.WIM is stored in sectors which then get corrupt? Isn't that a more serious issue that might affect access to the whole file, and therefore, the entire contents of the disk?

    Sure, that can happen. Just the same way your NTFS MFT may also get stored on a bad sector on disk and get corrupted, again losing your disk contents in the process. However, there's two copies of the NTFS MFT, precisely to prevent against total data loss in the case one copy gets damaged.

    I don't imagine there'd be two copies of the master file index for C:\DiskZIP.WIM, which is why I've quantified the risk of data loss as nearly identical, and not exactly identical. It seems to me there would still be a better chance of data recovery with NTFS MFT corruption, as compared to the chance of data recovery with C:\DiskZIP.WIM corruption.

    But in today's world where disk controllers do tons of built-in error correction and even sector relocation without skipping a breath (or without letting the OS know what's really going on), and especially where even the concept of a "sector" has become something of the past thanks to SSDs, the risk you're taking is basically just the risk of defective media. And that's the same risk you take any time you use a disk, around which there's only one thing: If you really want to protect your data, back it up, and more than once.

    If you're like the most of us, you won't back anything up until after disaster strikes, so if using transparent disk uncompression motivates you to backup ahead of that, all the better!

    Recompressing Your Disk

    Recompressing your disk is as easy as compressing your disk. The steps are fully identical, just click the big button that now reads "Recompress" instead of "Compress":


    When recompressing a previously compressed disk, DiskZIP Offline allows you to change the compression algorithm/acceleration type you used only if you use a Backup Disk. Without a Backup Disk, you will still be able to customize your compression boost, but you will not be able to change your previously selected acceleration type.

    Using a Backup Disk during recompression takes as long as the first time you compressed your disk, since all of your data is newly read and compressed freshly onto your Backup Disk. This is the safest way to do things, as no changes are made to your boot partition until your Backup Disk has been safely created.

    Not using a Backup Disk, DiskZIP Offline goes through recompression so much faster. It only compresses new files/folders added to the system, while recovering space from deleted files/folders. It does not recompress anything it had already previously compressed. This is riskier if something goes wrong during the process for any reason.

    I must admit I never use Backup Disks when recompressing, because it is so much faster without Backup Disks. When I am recompressing a 2 TB DiskZIP.WIM file, there's a huge difference between recompressing 2 TB of data versus the 10 GB of changes I made on disk. That's a difference in speed of roughly 200 times.

    You will want to periodically recompress your disk, after having compressed it with DiskZIP Offline. Think of this as a regular maintenance task on your PC, and schedule it the same way. On average, I recompress my disk about once a month to once every two months, but sometimes as frequently as once every couple of weeks. Below are three reasons I can think of for you to recompress your disk:

    1) Compress (and accelerate) new files, apps, updates added to your PC since your last compression pass.

    2) Recover space from files and apps deleted since your last compression pass. These are not automatically removed from C:\DiskZIP.WIM when you delete them, you must do a recompression pass to gain free disk space. Admittedly, this is the least convenient feature of DiskZIP Offline, and probably something done in favor of accelerating your disk at all costs, as opposed to maximizing free disk space in exchange for speed. Nonetheless, it does have some benefits as I have described below.

    3) Create a new "snapshot" of your operating system, apps, data, to act as baseline in case your PC gets infected by ransomware/malware, or to protect against accidental deletions via user error.

    This "snapshot" can remain on-disk, or you may copy it to an external drive to have a full secondary backup of your disk stored in a single file.

    Manually Extracting Files From A Compressed Disk Image

    It is of course possible to extract individual files/folders from either your "on-disk backup" or your external backup, which is a great thing - especially if you end up accidentally deleting or overwriting files, and need their originals as stored in the C:\DiskZIP.WIM file. You would just use any WIM file extractor for this (but ironically, DiskZIP's file compression stack itself seems to choke on the WIM image files it creates, as they often contain millions upon millions of files - sadly, this is the same with the open source 7-Zip project that DiskZIP's file compression stack is partially based upon).

    Since this can be so useful, I'll go ahead and give an example. Note - the steps below require command line processing and may not be for the faint of the heart:

    1) First, download the Windows binaries from https://wimlib.net/, which DiskZIP Offline itself referenced above in its advanced configuration page we covered earlier in this review.

    2) Next, extract the archive you downloaded, open an elevated command prompt, and change into that directory.

    3) Finally, type a command similar to this:

    wimextract c:\diskzip.wim 1 "\folder\to extract\inside wim\*" --dest-dir=c:\temp --preserve-dir-structure

    So basically, when you're typing the source path, you're using double quotes, and skipping the drive letter and colon designator for the path. That's all it takes to access/extract the original files inside the compressed disk image, even if you have since updated those files on-disk!
    Last edited: Apr 17, 2018
  3. msintle

    msintle Notebook Consultant

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    3. In Use - DiskZIP Offline, Approximating with Built-In Windows/Free Tools

    Unlike DiskZIP Online, there is really no straightforward way to approximate what DiskZIP Offline does using free tools, or those tools built into Windows. There's definitely nothing like a GUI or a compact.exe to compress your disk into a disk image file in a single step or two.

    There are things you can try. The WIMLIB package I referenced above does have command line tools to create WIM disk images. Microsoft presumably also has something similar in WIMGAPI (which WIMLIB is an improvement of). The workflow would basically have to be like so:

    1) You prepare a bootable USB drive with all the necessary disk access drivers.

    2) You boot from this USB and run wimcapture.cmd to create a compressed disk image manually on an external drive (think of this as the Backup Disk above).

    3) You format the partition you just captured, and copy the newly created compressed disk image onto this partition.

    4) You run the wimapply command in --wimboot mode to "mount" your compressed disk image, and reboot your PC.

    This is, after all, roughly what DiskZIP Offline does during processing. Of course, you'll have to manually:

    1) Figure out which files/folders to exclude from processing (the built-in default exclusion list that comes with WIMLIB may be a good place to start looking).

    2) Manually backup and restore file and folder exclusions before and after the creation of the disk image.

    3) There's no way to skip a Backup Disk requirement, unless you have at least 50% free disk space on the partition you're processing - this is because there's no option to delete compressed files on-the-fly with WIMLIB command line tools. So this option is quite impractical on PCs with disks nearly full, which DiskZIP Offline handles with grace.

    There's plently of WIMBoot tutorials out there on the Internet - but none of them seem to cover all of the steps above exhaustively, and none of them seem to support WIMBoot'ing an existing operating system - they are all designed to WIMBoot a new, clean installation of Windows.

    I frankly don't know if this is because it is impossible to WIMBoot an existing Windows installation with files, apps, and user data on it. I've never had to find out, thanks to DiskZIP Offline.

    With the steps above, it should be theoretically possible. But there's no way to know for sure, and I am wondering if there's some secret sauce to DiskZIP Offline, given the absolute lack of non-clean-machine WIMBoot tutorials out there.

    Feel free to try it out and let us know what you find - it won't be easy, but it may be worthwhile.

    So this concludes our extensive coverage of DiskZIP Offline - we have only one tool left to review, named the DiskZIP Accelerator! Coming up next...
  4. msintle

    msintle Notebook Consultant

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    3. In Use - DiskZIP Accelerator

    This is the final tool I will be discussing in my review (as I mentioned earlier, I am excluding DiskZIP Max from this review):


    Launching this tool is extremely easy. Click the DiskZIP icon on your Taskbar, or Start Menu, whichever you prefer. The icon created by the installer launches this tool, which is great after you've compressed your disk (but not before, because the tool does nothing until you've actually compressed your disk).

    Let's take a look at the available buttons in this tool.

    Compress: Simply launches DiskZIP Offline. Nothing new here.

    Tune: This is new and interesting, if not exactly useful. Take a look:


    The software reads your existing compression ratio on your DiskZIP Offline compressed disk. For my tablet here, the ratio is 2.1:1, which means I have more than doubled my storage.

    So far so good - but what does this tune thing do? Here, take a look. This is with the tuner set to 1.0:1. To move the tuner, simply move the slider up or down. So with the trackbar set all the way to the top and then "Save" clicked:


    This is the truth, actually. Now, let's lie a little. Move the slider all the way down to the bottom and click "Save". This is what you get:


    So what's going on here? Take a look at what it looks like at the recommended medium setting (2.1:1):


    It's all the same partition. But the software is making the disk appear bigger or smaller, based on the compression ratio selected here.

    This is just what the old DOS software used to do as well. When you're compressing your disk, you can store more than your raw free disk space would report. However, with DiskZIP, its not entirely useful. This is because, by default, DiskZIP does not compress data on-the-fly.

    And even if you enable on-the-fly data compression, keep in mind its just falling back to NTFS compression, which is a whole lot weaker than DiskZIP Offline's custom compression. So while you can nicely make it look like your disk is as big as your compression ratio indicates, in real world use, you actually cannot use your remaining free disk space as if it was being compressed on-the-fly.

    This is surely the most gimmicky feature of the entire DiskZIP suite. Nice to show off all that extra disk space you've gained, but useful for nothing else.
    Last edited: Apr 19, 2018
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  5. msintle

    msintle Notebook Consultant

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    Optimize: This just launches DiskZIP Online, so nothing new here either.

    Report: This is new again, and definitely more useful. It goes through each file on your disk to thoroughly calculate your compression ratio:


    The ratio will keep changing as more files are scanned. It will eventually end up being lower than what is shown in the startup screen of this tool, most probably because of uncompressed files which are in excluded folders that end up lowering your compression ratio. Also, as you overwrite existing files and write new files to disk, these too would be in an uncompressed state, again lowering your ratio.


    When this scan is done (which you may cancel at any time), you get a thorough report of your uncompressed size, and your compressed size, and the space you have saved with compression. There's still something a little funny about this report. Take a look at my partition setup here:


    My boot partition is 564 GB. The compressed data totals 1 TB, so I'm definitely squeezing nearly double the data on this partition that I would ordinarily be able to store - great job, DiskZIP Offline! However, my compressed size is reported to be 671 GB, which still wouldn't fit in 564 GB (and I do have a few tens of gigs still available on my C: drive). DiskZIP reports that I've saved 375 GB of space, which is really nice - but either the compressed size estimate is wrong, or something else is - because the numbers don't add up to the reality of the partition size.

    If I actually calculate file sizes using Windows File Explorer (selecting every file and folder at the root of Drive C:, and then clicking "Properties"), this is what I get in turn:


    As you can see, that definitely looks a whole lot crazier and unreal. So the plot definitely thickens, and I'm not entirely sure how to account for all of these discrepancies in something that should be as obvious and simple as disk space reporting! I won't dwell on this though, because it appears to be a cosmetic issue with no real-world ramifications - if anyone else figures this out though, I'd love to hear about how you solved this puzzle!

    Anyways, dismissing this window, you are put back into the Tune section, so you can apply the accurate compression ratio you just spent a while calculating (yes, the tool scans the entire partition, so it takes a while). You can then apply that updated ratio if you wish.

    Just keep in mind that even with a super accurate ratio, the Tune setting is still a gimmick. This is because with the recommended defaults, DiskZIP will not compress files on-the-fly, so no matter how well the rest of your disk is compressed, you still cannot automatically assume your free disk space is going to hold more than it normally can, at least not until DiskZIP Offline compresses your disk again.

    So this is the chicken-egg problem with disks overflowing with data - you theoretically can fit more data in, but sooner or later, you're going to run out of the necessary "temporary storage" where you can store that data until it gets compressed. The DOS tools certainly did not have this issue, so if I were to speculate, I'd reckon the NTFS kernel is way more restrictive in this regard.

    Check: This is the most useful of the bunch in this tool. It checks your disk for corrupted files, as well as for space that can be recovered when you recompress it with DiskZIP Offline - which is actually a very actionable, useful report:


    The Garbage Data field here indicates files which have been deleted and/or updated since your last offline compression pass with DiskZIP Offline. It is space that is guaranteed to be recovered when you recompress your disk, but not before.

    The New Data field indicates which files are uncompressed due to their having been added after your last offline compression pass with DiskZIP Offline. It is space that can be compressed so you can expect some space recovery from compression, although not all of that space can be recovered as in the Garbage Data field.

    The Corrupted Files field indicates the number of files which have been corrupted on disk due to DiskZIP. In 99.99% of cases where I have run DiskZIP, this field has remained at 0 - zero.

    In nearly two years of my using DiskZIP Offline, to date I have had only one time where this field read "2", and that was for some files stored in the Recycle Bin. The tool in this case displayed the paths of the files that were corrupted and offered to delete them, unfortunately no recovery option was available.

    This type of corruption therefore appears to be extremely rare. I don't know if I had emptied the Recycle Bin before running DiskZIP Offline - that is my guess - but maybe DiskZIP Offline does run into issues occasionally with the corruption of files stored in the Recycle Bin. Your guess is as good as mine, to be honest - and in fairness, I feel I had to report this, especially considering how concerned people are with reliability.
    Last edited: Apr 19, 2018
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  6. msintle

    msintle Notebook Consultant

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    So when the process is complete (which again takes a while to comb through your entire disk), you get a nice and useful summary:


    Unfortunately, my attempts to reproduce the issue with the corrupted files in the Recycle Bin failed in my attempts with virtual machines, so I have been unable to produce a screenshot illustrating how corrupted files are displayed/handled here. I do remember that their full path was shown, together with the option to delete them.

    All in all, while I would have liked more transparency into what went there, I am letting it slide given how it has been the only incident I've had in two years. It would have of course been better, had DiskZIP offered to repair the corruption instead of just deleting the files. So again, in the spirit of full disclosure, no matter how much I love this product and feel super safe with it, I thought I had to let you all know. I owe it to you as your reviewer! Otherwise, it may simply have all been caused by generic file system corruption/a bug in Windows, for all I know.

    This actually concludes our section #3 - where I've attempted to describe each component in great detail.

    4. Competing product discussion

    This section is real easy. There's actually no other disk compression products that I'm aware of! So DiskZIP Offline has no competition. Really.

    In a sense, you may consider the ways I described above in section #3 to approximate what DiskZIP does competing products, but they're not really products at all - so I feel justified skipping this section entirely, having earlier provided the approximations (again, none of which are really products).

    5. Benchmarks

    I don't believe I am qualified to conduct in-depth benchmarks of this software, so I will keep this section short as well. This was one of the first questions asked near the start of my review, where I posted official DiskZIP benchmarks.

    In my experience, these benchmarks are true, and I would love if someone skilled in these matters could compile some additional benchmarks on their hardware.

    If we had a benchmark for each type of disk - that would be great!

    Thank you for your understanding here, and I hope my reaching out to the community for help with this one is not inappropriate.

    6. Bulleted Pros/Cons:

    Wow, here we are - at the very end of this admittedly very long review!

    If you made it so far, thank you.

    Here's my list:

    More disk space without performance loss!
    A layer of protection against ransomware
    Entirely undoable and as safe as possible
    At the discounted prices, a no-brainer

    For best compression, must process disk offline
    Loss of space requiring periodic recompression
    Last edited: Apr 19, 2018
    Maleko48 likes this.
  7. Frosti

    Frosti Notebook Enthusiast

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    I would like to try, but am very time constrained (and space constrained as i dont have a space for backup before trying DiskZip)

    My question:
    I have 8TB of video's.
    I know that videos are already compressed and cant be helped with ZIP/RAR
    Would DiskZip help in anyway? or like a standard ZIP drive it wont make a difference?

  8. msintle

    msintle Notebook Consultant

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    It wouldn't help at all, other than buying you a few tens of gigabytes from compressing the non-video program files stored on your system (Windows, Office, etc.)

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