Dne 21. 07. 25 v 18:42 matthew patton napsal(a):
don't use LVM striping. Use MD/DM striping. Better yet, stripe at the hardware
lvm handles both --type striped, type raid0
controller level if you can. Generally speaking a 32kb or 64kb interleave or
"strip size" is ~optimal for any use case (yes, even SSD) that isn't LARGE
Many/most SSDs do internal striping - thus they go with relatively large
optimal io sizes (256K, 512K)
streaming reads. If the hypervisor is VMware, it allocates in 1MB extents and
it will also interfere with I/O scheduling.
If you want to cut the hypervisor out of the loop, PCIe pass-thru is your only
recourse. And again, you can attach no less than 3 up to about 5 (SSD) drives
This purely depends on individual hw capabilities.
to a controller before you saturate the PCIe bus. Also consumer-grade (aka
junk) SSDs have miserable write endurance and write speed after a preliminary
(ie fake) boost. If you care about your data and speed that doesn't go to zero
ONLY buy enterprise grade SSDs and if you're doing a lot of writes, minimum 3x
DWPD class though if you're going to attempt parity-RAID, you'll want 10x DWPD
disks.
For boosting write performance there is probably a better option to simply use
some nvme caching with dm writecache or something like that.
But as said - trying to do any kind of storage optimization inside VM is
largely destined to fail - as there is not good enough knowledge about disk
topology - since VM fakes whatever it can...
Regards
Zdenek
