Storage Spaces replace drive slow

Marc Al 156 Reputation points


I have decided to play with Storage Spaces (win11) to see how it works (if it could replace my old home server with a RaidZ2 (4+2) drives so I have decided to use parity (simple mirror with my old drives)

So I create a pool (GUI)

Then I create the hard drives with interleave of 16K

New-VirtualDisk -StoragePoolFriendlyName "MainPool" -ProvisioningType Thin -Interleave 16KB -FriendlyName "Main" -Size 10TB -ResiliencySettingName "Parity" -PhysicalDiskRedundancy 1  -NumberOfColumns 5

Then I format (NTFS) with a cluster of 16K as refs is not working anymore on Win11

I copy about 2TO (to have a small test, with 100 Go there is no problem) (about 115 Mo/sec in a gigabit network from the old server).

After that I remove one WD RED (version 4K) The 6 drives I used have been, working together in a zfs pool 4 years with no speed problem and put another one

And I do the repair

  1. Retire the missing drive
  $ProblemDisk = Get-PhysicalDisk | where-object OperationalStatus -like *lost*
 $ProblemDisk | Set-PhysicalDisk -Usage retired

  1. Add the new drive

$DiskToAddToPool = Get-PhysicalDisk | where-object Canpool -eq True

Get-StoragePool MainPool | Add-PhysicalDisk -PhysicalDisk $DiskToAddToPool

  1. Wait till it is over
while(1 -eq 1) {
 write-host 'Wait'
 start-sleep -seconds 10

In the beginning it is really fast (0, 400 Go/ 10 sec.) (40 Mo/sec.)
But after a few hours I am at about 1-3 Mo / sec (50 sec. to do 0.01 GB) for example(here 200 Ko / sec).

There has never been a delete (only a copy from a network drive so files souldn't be fragmented).

The computer is not used during the repair

After 6H16 I have done 201.4 GB (of 467.5 GB) 43%

With the same drives ( in my Raid ZPool ) filled with about 10 To(4 years of create / delete... so fragmented) it took about 16-17 hours to replace a drive.

Is there something I am missing ? It can't be that slow compared to ZFS ?

Thank you

When It is done I will do

Optimize-StoragePool -FriendlyName MainPool

And after that I will do

$RetiredDisk = Get-PhysicalDisk | where-object  Usage -like *Retired*
Get-StoragePool -FriendlyName MainPool | Remove-PhysicalDisk -PhysicalDisk $RetiredDisk

Windows 11
Windows 11
A Microsoft operating system designed for productivity, creativity, and ease of use.
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  1. Limitless Technology 44,091 Reputation points

    Hello there,

    When you encounter a slow drive replacement process in Storage Spaces, there can be several reasons for this behavior. Storage Spaces is a technology in Windows Server (and Windows 10 Pro/Enterprise) that allows you to pool physical drives together to create a virtual storage space, providing redundancy and performance benefits. Here are some possible reasons and solutions for slow drive replacement:

    Drive Rebuild Time: When a drive fails in a Storage Spaces pool, the system initiates a rebuild process to redistribute the data and restore redundancy. This process can be time-consuming, especially if the pool is under heavy load or if the new drive has a different speed or size than the original one.

    Solution: Be patient and allow the rebuild process to complete. Depending on the size of the pool and the amount of data, it might take several hours or even longer.

    Drive Speed and Health: If the new drive is slower or less healthy (i.e., has bad sectors or other issues), it can impact the rebuild process and lead to slower performance.

    Solution: Ensure that the replacement drive is healthy and has similar or better specifications (speed, size, and type) than the original drive. If possible, use enterprise-grade drives optimized for RAID and Storage Spaces.

    Background Maintenance: Storage Spaces performs background maintenance tasks, such as integrity scrubs and tier optimization, which can impact performance while the rebuild is ongoing.

    Solution: Avoid heavy I/O operations on the pool during the replacement process. Limit background maintenance tasks if possible.

    I used AI provided by ChatGPT to formulate part of this response. I have verified that the information is accurate before sharing it with you.

    Hope this resolves your Query !!

    --If the reply is helpful, please Upvote and Accept it as an answer--

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  2. Marc Al 156 Reputation points


    Thank you for the hint (I have made a completely new test so it took time to copy datas...))
    After another test, the problem is still the same. A repair with about GB to rest To to restore is "impossible". Everything is "disabled" on the computer and it is left on with no one on it

    When it is too slow, a simple reboot makes it - times faster (but still at - Mo / sec (so days to restore a backup)

    The 6 hard drives for the tests have been used together during 6 years (2300 days) with no problem. With a mirror all is fine too (no slowdown) so it is really a problem with the 4 + 1 repair disk (all usage is at 0%)

    (seeing how it slows down, it would take days to repair (300 Go even at 1 Mo / sec) ==> 83 hours with an impossible to use system (access to the disk too slow).

    While a simple destroy / Copy is 10 times faster. I can't even imagine a full backup of 10 To (it seems the slow down is exponential). It would take years. I have upgraded my computer and to some other tests.

    PS : The disk controler is a SAS disk in Pci Express

    Thank you again


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  3. Marc Al 156 Reputation points


    I think that there is a problem with the advancement because with another computer (i7 13770K) it started 3 times faster and after that it was still as slow (about 1 MB / sec. a few hours) and suddenly it went from about 60 % to 100% .

    Thanks again for the time

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  4. Alex Bykovskyi 1,506 Reputation points


    Have you tested performance of your parity Storage Spaces VD? The following article might help with performance:

    Write performance of VD will have an influence on the rebuild speed. It should help.

    As another option, you can go with StarWind SAN&NAS to build RAID (ZFS or MDADM).

    Alex Bykovskyi  
    StarWind Software  
    Note: Posts are provided “AS IS” without warranty of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability and/or fitness for a particular purpose.

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  5. Marc Al 156 Reputation points


    Thank you for the answer.

    I have already used the first link

    What I can do (at the moment) is use a virtual machine to install a linux distro (Truenas scale Openmediavault...) and passthrough the hard drives to do make a ZFS pool but in that case I can't use the intreresting features of Windows (samba compression...)

    Or I can do a ISCSI drive (from linux to Windows but I was hoping to do it directly).

    Thanks again


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