Virtio disk type is much faster then iscsi disk type in VM?

[werter]

Hi there )

Virtio disk type is much faster then scsi disk type ?
Controller type for both: Virtio scsi single.

fio:
fio --name=fiotest --filename=/mnt/diskX/test1 --size=4Gb --rw=randrw --bs=8K --direct=1 --rwmixread=50 --numjobs=8 --ioengine=libaio --iodepth=32 --group_reporting --runtime=60 --startdelay=60

scsi:
...
Run status group 0 (all jobs):
READ: bw=676MiB/s (708MB/s), 676MiB/s-676MiB/s (708MB/s-708MB/s), io=16.0GiB (17.2GB), run=24237-24237msec
WRITE: bw=676MiB/s (709MB/s), 676MiB/s-676MiB/s (709MB/s-709MB/s), io=16.0GiB (17.2GB), run=24237-24237msec

Disk stats (read/write):
sda: ios=2089129/2091635, merge=0/1, ticks=2290806/2297572, in_queue=4598849, util=99.45%

virtio:
...
Run status group 0 (all jobs):
READ: bw=840MiB/s (881MB/s), 840MiB/s-840MiB/s (881MB/s-881MB/s), io=16.0GiB (17.2GB), run=19495-19495msec
WRITE: bw=841MiB/s (882MB/s), 841MiB/s-841MiB/s (882MB/s-882MB/s), io=16.0GiB (17.2GB), run=19495-19495msec

Disk stats (read/write):
vda: ios=2092572/2095010, merge=0/1, ticks=2102793/2106556, in_queue=4219697, util=99.57%

Question 1:
Why Proxmox team recommends the use of a scsi disk type here https://pve.proxmox.com/wiki/Windows_2012_guest_best_practices or here https://pve.proxmox.com/wiki/Windows_10_guest_best_practices ?

Question 2:
Why I can't choose SSD emulation with virtio disk type? Is it bad if the VM disk on ssd pool ?

Thx for answers

 

[zzz09700]

Why I can't choose SSD emulation with virtio disk type? Is it bad if the VM disk on ssd pool ?

That's generally bad for Windows VM and nothing else.

 

[leesteken]

Why I can't choose SSD emulation with virtio disk type?

VirtIO Block usually lags a bit in features compared to VirtIO SCSI.

 

[werter]

That's generally bad for Windows VM and nothing else.

Only for Win VMs?

 

[werter]

VirtIO Block usually lags a bit in features compared to VirtIO SCSI.

But as u see above Virtio disk MUCH faster. Why ?

 

[bbgeek17]

Here is a brief overview of when one might want to enable ssd emulation:
https://bobcares.com/blog/proxmox-ssd-emulation/

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Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

 

[werter]

Here is a brief overview of when one might want to enable ssd emulation:
https://bobcares.com/blog/proxmox-ssd-emulation/

---

Blockbridge : Ultra low latency all-NVME shared storage for Proxmox - https://www.blockbridge.com/proxmox

Thx