1.    03 Jan 2016 #1
    Join Date : Nov 2015
    Posts : 114

    BitLocker Encryption process VERY Slow on Win10

    I just installed Win10 Pro and I love it.
    When I enabled BitLocker, I selected to encrypt the Entire drive instead of the Used Space because I just feel I am safer with encrypting the entire drive. And my drive is not new. It had Win7 running before.

    So I did a clean install of Win10 pro with BitLocker enabled to set to encrypt the ENTIRE drive.
    The encryption process took 7 hours to complete on a 300GB internal disk drive

    When I had Win7 (and even Win8.1), it did not take that long to encrypt and I have the same exact internal drive.
    In Win7, the whole process took 1 hour. And with Win8.1 took a bit more time, but not 7 hours...

    Why is entire disk encryption takes this long on Win10?

    And also, I do not have a whole lot of programs installed. I have like 6 programs installed and there not that huge in size.

      My System SpecsSystem Spec

  2.    08 Jan 2016 #2
    Join Date : Jan 2016
    Posts : 5
    Win 10 Pro 64bit

    Quote Originally Posted by win10freak View Post
    Why is entire disk encryption takes this long on Win10?
    I don't know why this is, but it is ULTRA SLOW indeed. I recently bought a WD Blue 4 TB drive and Bitlocker is already encrypting it for more than 50 hours and is still at only at 68.3%.

    According to the Windows Taskmanager the Bitlocker process is using the drive at 100%, constantly reading off and writing on it at 7-15 MB/s. I don't know about the mechanics of a harddrive, but running at 100% for 75 hours (>3 days!) isn't going to improve its health.

    I chose the offered new encryption XTS-AES.

    In the past, encrypting a whole drive always took some time, but even with drives as big as 3 TB it never took more than 24 hours.

    I guess it is some kind of bug and i hope that Microsoft will fix it.

      My System SpecsSystem Spec

  3.    09 Jan 2016 #3
    Join Date : Oct 2014
    Canon City, Colorado
    Posts : 43
    Windows 10 Pro 64 Bit Build 1607

    If I may ask are you on a HDD or a SSD? I know my 250 GB SSD took about 2 hours to encrypt with the XTS-AES 256 Bit encryption for the whole drive. I know I have not been pleased with Windows 10 performance on the HDD in my wife's computer.

    Now I think Microsoft has just finally fixed many of the security problems with Bitlocker as I have always read that Bitlocker is a good encryption but has loop holes. At my work with our slow role out of Windows 10 we have started to use Bitlocker but I do know on our Windows 7 machines when using TrueCrypt in the past and DiskEncryptor to do a full drive 256 Bit encryption on a 500GB drive typically takes around 7-9 hours depending on the generation of Intel CPU as many of the machines that are 2nd Gen i3 still running around.

    I do know what your saying that Bitlocker in the past did encrypt faster but I always questioned on how that was when I have used so many other encryption tools that took so much longer. Personally I feel safer to see Bitlocker taking around the same time that every other software I have used in the past.
      My System SpecsSystem Spec

  4.    09 Jan 2016 #4
    Join Date : Jan 2016
    Posts : 5
    Win 10 Pro 64bit

    Did you address me or the OP?

    My drive is an internal SATA3 HDD. It is still encrypting btw Right now it is at 92%. So my ETA is in a couple of hours or 3 1/2 days total. Granted I used the PC and the disk a couple of times today, which seems to interrupt the encryption process. Btw. copying files to and from the disk works with 110 - 150 MB/s throughput (avg. 120-130 MB/s). That's what I usually get from SATA3 connections.

    For purposes of comparison I started to encrypt a 1 TB WD Blue SATA3 HDD in an external USB 3 case and that went considerably quicker. The Bitlocker process wrote and read at around 50 MB/s and finished within a couple of hours today.

    Since you mentioned it: Encrypting SSDs under Win 10 wasn't without its issues for me, either. While you could easily use Win 8/8.1 while encrypting a SSD, the encryption process under Windows 10 sucked all the life out of the two PCs I encrypted (both powerful machines). The advantage may be, that the encryption finishes fast, but it still sucks if you actually wanted to work in the meantime.
      My System SpecsSystem Spec

  5.    16 Jan 2016 #5
    Join Date : Feb 2014
    Posts : 472

    Yeah, if you opt to do the whole disc in one go then it can take a while. I found for SATA drives, the time taken to encrypt using XTS-AES 128, at opposite ends of the spectrum, were approximately as follows:

    1TB HDD, SATA II motherboard with non AES-NI supported Processor = Approx. 28 Hours

    1TB SSD, SATA III motherboard with AES-NI supported Processor = Approx. 12.5 Hours
      My System SpecsSystem Spec

  6.    16 Jun 2016 #6
    Join Date : Jun 2016
    Posts : 1
    Windows 10 Pro

    To get a 5x speed boost on encrypting your full drive in Windows 10:
    1. Enable Bitlocker in the running OS, but pause the encryption once it's in progress
    2. Create a recovery disk, boot it up, go to command line
    3. Resume encryption of the drive using "manage-bde -resume" while in the recovery environment
    (4. Pause again at 99% and go back to the running OS and finish it from there...? This is probably unnecessary, but this is what I did.)


    I just tried to encrypt my 2TB external HDD on the latest Windows 10 Pro using Bitlocker (entire drive, compatible mode), and since I only got to 3% within ~2 hours, I started looking into what was going on. I checked on Task Manager's Performance tab, and while CPU and memory was idling, disk usage on the affected drive was at 100% constantly. However, at the same time, it reported 10 MB/s read and also 10 MB/s write, which was very slow compared to how this drive performs when I read / write files myself. This is when I started searching the internet and found this thread.

    First I wanted to obtain a Windows 8.1 Recovery Disk, to try to boot it up and encrypt the drive from the command line tool "manage-bde", hoping that it would be a lot faster as reported here. However, I wasn't able to find an ISO for that recovery disk, so I gave up on that. But as a last effort, I decided to try the same with the Windows 10 Recovery Disk that I could simply create from my running OS. And the trick worked!

    Windows 10 Pro (same machine, same drive, same everything!), Running OS vs. Recovery Disk
    (I will just post the results in "percent per hour", as it shows the speedup just fine, but if you'd like, you can calculate MB/s.)

    === Encryption phase 1 - Running OS ===
    20:13 - 0.0%
    00:01 - 5.9% --> 1.553% per hour

    === Encryption phase 2 - Recovery Disk ===
    00:08 - 5.9%
    00:39 - 11.0% --> 9.871% per hour
    02:07 - 25.3% --> 9.750% per hour
    04:44 - 50.0% --> 9.439% per hour
    11:41 - 99.2% --> 7.079% per hour

    === Encryption phase 3 - Running OS ===
    12:10 - 99.2%
    12:41 - 100.0% --> 1.548% per hour

    === Results ===
    Running OS: average 1.55% per hour; estimated total 64.5 hours
    Recovery Disk: average 8.08% per hour; estimated total 12.4 hours
    SPEED UP: ~5x

    My guess is that Windows 10 is throttling the encryption process to a "safe speed" for some reason, probably to keep the system usable while it's working. You can see that the processing speed is approximately the same at the start (~0%) and at the end (~100%) when the OS is running, whereas it gradually slows as we get to the slower parts of the disk while encrypting in the recovery environment. So basically the disk IO is really maxed out in the recovery environment, while the bottleneck is somewhere else in the running OS.
      My System SpecsSystem Spec


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