VHD bad performance. Slow read & write.

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VHD bad performance. Slow read & write.

Postby doonay » 28. Feb 2021, 13:52

Hi,

My hardware is HP DL380 g8 controller is HP Smart Array P420/1GB. OS Windows Server 2019 on SSD, 5x2TB SATA HDD raid 5, 2X1TB raid 0.

Copying files between for example raid 5 to SSD 200-250MB/s

Copying files between vhd hdd is 15-30 MB/s
Windows 10 or Linux virtual machine no difference.

There is no difference if vhd is on ssd or raid 5 or raid 0. The speed is the same 15-30 MB/s

I tried check and uncheck Use Host I/O Cache in also no difference. Controller ahci.

I tried enable / disable Smart Array P420 cache settings but also no differance.
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Re: VHD bad performance. Slow read & write.

Postby scottgus1 » 28. Feb 2021, 15:53

VM processing power can influence data throughput. Since you have a Windows host, you could mount the VHD to the host while the VM is not running, and test VHD access speeds using just the host OS. Keep in mind that the most illuminating speed test may be with the VHD and the data to be copied both on the SSD, thus removing the platter disks' head seek and movement times from the equation. (You don't need to disconnect the VHD from the VM to mount it on the host OS. But the VM has to be shut down. Also, no snapshots in the VM. Unmount the VHD from the host before restarting the VM.)

If your VHD is dynamic-expanding, it is at risk of complete data failure. VHD has a design flaw that will kill the data if the host has an error or glitch while the VHD is getting bigger. Fixed-size VHD also has the design flaw but does not get bigger, so the design flaw does not get triggered. If your VHD is dynamic-expanding and you don't need to mount the drive file to the host in normal use, consider converting the VHD to Virtualbox's native VDI.
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Re: VHD bad performance. Slow read & write.

Postby doonay » 3. Mar 2021, 16:54

Thanks for your reply.

Info about dynamic-expanding very importatnt form me.

On Hyper-V is perfectly fine. Speed is totaly right.
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Re: VHD bad performance. Slow read & write.

Postby doonay » 4. Mar 2021, 00:24

I need to run xpendology on this server but on Hyper V wont work. What to do?
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Re: VHD bad performance. Slow read & write.

Postby scottgus1 » 4. Mar 2021, 01:18

What are the results of the speed with the VHD on the SSD and mounted in the Windows host OS as I described above?
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Re: VHD bad performance. Slow read & write.

Postby doonay » 4. Mar 2021, 09:28

From VHD on SSD to RAID 5 175MB/s
From VHD on SSD to RAID 0 5x500GB 178MB/s
From RAID 5 to VHD on SSD 162MB/s
From RAID 0 to VHD on SSD 400MB/s :shock:
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Re: VHD bad performance. Slow read & write.

Postby doonay » 4. Mar 2021, 09:33

Vmware also was have this problem on older version.

https://kb.vmware.com/s/article/1036961
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Re: VHD bad performance. Slow read & write.

Postby scottgus1 » 4. Mar 2021, 17:58

Start the VM from full power off, not save-state. Try the speed test while the VM is running, then shut down the VM from within the VM OS if possible. If not possible, close the Virtualbox window for the VM with the Power Off option set.

Please right-click the VM in the main Virtualbox window's VM list, choose Show Log. Save the far left tab's log, zip the log file, and post the zip file, using the forum's Upload Attachment tab.
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Re: VHD bad performance. Slow read & write.

Postby doonay » 5. Mar 2021, 11:41

Log. I was also test it on Vmware Worstation pro. Speed is 60-70MB/s acceptoble for 1GB network NAS but no perfect :cry:
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Re: VHD bad performance. Slow read & write.

Postby scottgus1 » 5. Mar 2021, 17:48

doonay wrote:Copying files between vhd hdd

doonay wrote:On Hyper-V is perfectly fine. Speed is totaly right.

doonay wrote:From VHD on SSD to RAID 5 175MB/s
From VHD on SSD to RAID 0 5x500GB 178MB/s
From RAID 5 to VHD on SSD 162MB/s
From RAID 0 to VHD on SSD 400MB/s


the posted log wrote:Guest disk files:
00:00:12.422066 File system of 'C:\Maszyny\Xpendology\synoboot.vdi' is ntfs
00:00:12.424456 File system of 'F:\VHD\Xpendology_2.vdi' is ntfs
00:00:12.426701 File system of 'D:\Xpendology_3.vdi' is ntfs
00:00:12.429567 File system of 'D:\Xpendology_4.vdi' is ntfs
...
00:00:13.128154 Path <string> = "C:\Maszyny\Xpendology\synoboot.vdi" (cb=35)
00:00:13.128187 Path <string> = "F:\VHD\Xpendology_2.vdi" (cb=24)
00:00:13.128207 Path <string> = "D:\Xpendology_3.vdi" (cb=20)
00:00:13.128227 Path <string> = "D:\Xpendology_4.vdi" (cb=20)


There are no VHD's in this posted VM log, only Virtualbox's native VDI. According to my web-searches, Hyper-V can't use VDI as a disk format. Where's the VHD?
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Re: VHD bad performance. Slow read & write.

Postby doonay » 5. Mar 2021, 19:06

My mistake it shul be VDI no VHD.
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Re: VHD bad performance. Slow read & write.

Postby scottgus1 » 5. Mar 2021, 19:09

doonay wrote:it shul be VDI no VHD.

Accuracy is important. All the talk of 'vhd' above was thus wasted time.

You cannot mount a VDI to a Windows host OS, as I suggested when you were talking about a VHD:
scottgus1 wrote:you could mount the VHD to the host while the VM is not running, and test VHD access speeds using just the host OS


When I asked:
scottgus1 wrote:What are the results of the speed with the VHD on the SSD and mounted in the Windows host OS as I described above?

you reaponded:
doonay wrote:From VHD on SSD to RAID 5 175MB/s
From VHD on SSD to RAID 0 5x500GB 178MB/s
From RAID 5 to VHD on SSD 162MB/s
From RAID 0 to VHD on SSD 400MB/s


If you were talking about a VDI, you could not have carried out the test I suggested, it was impossible.

what were you reporting?
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Re: VHD bad performance. Slow read & write.

Postby doonay » 5. Mar 2021, 19:15

From VHD on SSD to RAID 5 175MB/s
From VHD on SSD to RAID 0 5x500GB 178MB/s
From RAID 5 to VHD on SSD 162MB/s
From RAID 0 to VHD on SSD 400MB/s

This test was on HYPERV vhd.

On VirtualBox i am using vdi. In virtual box there is no difference wher virtual disk is transfer i always 20-40MB/s. I was also test vhd in VirtualBox but performace was the same.
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Re: VHD bad performance. Slow read & write.

Postby doonay » 5. Mar 2021, 19:21

Sorry, thanks for your help.
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