Poor I/O Performance PM 8.2.2

[gregor.klatovsky]

Hi,
I've read serveral threads concering a poor disk performance in a Windows guest vm running on proxmox.
I have not found anything which could fix the problem. The guests are setup as described in any tutorial, latest virtio driver, SCSI disk with write back, virtio SCSI single controller aso.
The storage is a brand new qnap with 4 TB SSD disk. QNAP performance tests show the proper value of I/Os and MB/s. The proxmox shell also shows also the proper value (tested with fio). Only the Windows guest (Windows Server 2022) has a very poor disk performance.
Doese anybody has a clue why there is such a bad performance. I think it is a common problem, if I google the issue a lot of threads were shown.
Thanks a lot
Gregor

 

[Maximiliano]

Hello,

What filesystem is used inside of the Windows host? What filesystem are you using for storage on the Proxmox VE side? For how long did you run such benchmarks? What kind of SSD disk is this? Which model?

 

[gregor.klatovsky]

Hi Maximilliano,
thanks for your reply. The Windows FS is NTFS. The filesystem is ext4 for the local and the ISCSI disks raw. The benchmarks ran about 20 minutes. I use 4 WD RED SA500 NAS SATA SSD 4TB with RAID5 on a QNAP. One separate backbone with 10G is also there.
Thanks al lot
Best Regards
Gregor

 

[gregor.klatovsky]

Hi,
I also did a FIO test on the SSD storage. The outcome is in my eys very good, but the Windows Disk Performance is very ugly:

fio --name=vgtest --ioengine=libaio --rw=randwrite --bs=4k --num jobs=4 --size=10G --runtime=60 --group_reporting --filename=/dev/VG_SSD/old-100-1

vgtest: Laying out IO file (1 file / 10240MiB)
Jobs: 1 (f=1): [_(2),w(1),_(1)][100.0%][w=929MiB/s][w=238k IOPS][eta 00m:00s]
vgtest: (groupid=0, jobs=4): err= 0: pid=676453: Fri Oct 18 11:36:45 2024
write: IOPS=438k, BW=1711MiB/s (1794MB/s)(40.0GiB/23938msec); 0 zone resets
slat (usec): min=2, max=3440, avg= 7.39, stdev= 3.61
clat (nsec): min=796, max=87343, avg=857.97, stdev=245.86
lat (usec): min=2, max=3444, avg= 8.25, stdev= 3.63
clat percentiles (nsec):
| 1.00th=[ 820], 5.00th=[ 828], 10.00th=[ 828], 20.00th=[ 836],
| 30.00th=[ 836], 40.00th=[ 836], 50.00th=[ 844], 60.00th=[ 844],
| 70.00th=[ 844], 80.00th=[ 852], 90.00th=[ 868], 95.00th=[ 900],
| 99.00th=[ 1160], 99.50th=[ 1320], 99.90th=[ 3568], 99.95th=[ 4896],
| 99.99th=[13888]
bw ( MiB/s): min= 1558, max= 2487, per=100.00%, avg=1811.62, stdev=71.81, sa mples=176
iops : min=398886, max=636681, avg=463775.87, stdev=18382.28, samples= 176
lat (nsec) : 1000=98.33%
lat (usec) : 2=1.53%, 4=0.05%, 10=0.07%, 20=0.02%, 50=0.01%
lat (usec) : 100=0.01%
cpu : usr=15.50%, sys=84.44%, ctx=6313, majf=0, minf=348
IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
issued rwts: total=0,10485760,0,0 short=0,0,0,0 dropped=0,0,0,0
latency : target=0, window=0, percentile=100.00%, depth=1

Run status group 0 (all jobs):
WRITE: bw=1711MiB/s (1794MB/s), 1711MiB/s-1711MiB/s (1794MB/s-1794MB/s), io=40 .0GiB (42.9GB), run=23938-23938msec

Pls help
thx