Dne 18. 07. 25 v 16:46 Henry, Andrew napsal(a):
Dne 18. 07. 25 v 14:24 Henry, Andrew napsal(a):
Maybe you virtual system does have it self 'a single write pipe' - so any
parallelization is stopped right there - so maybe you should start first with
bare metal....
This is what I suspect is happening, as the back-end storage is very fast. I'm
going to test on a physical server instead.
/AH
It's crucially important to be sure - you have independent drives & controller
paths to them.
It's really pointless trying to setup a 'stripe' on top of 3 drives that are at
the end served by a singly physical storage behind the scene - this likely can
explain rather horrible numbers you get when you are trying to use stripe
- in such case simply join devices 1-by-1....
Zdenek
I re-tested this on a consumer PC.
SATA6 controller, 2 * 1TB Seagate 4ke drives with product spec of ~210MB/s read
speed and ~160MB/s write speed.
Created the lv as follows:
Plus all these results are sort of inline with the physical characteristics of
the drives max R/W speeds.
When I perform same procedure on a VM using the paravirtualised driver for the
3 controllers, I'm not getting speeds in-line with what I expect from solid
state storage. Obviously, striped LVM in a VM with storage pool connected to
the VM host just does not work the way it would with separate physical devices.
So the short answer here can be - never try to 'stripe' anything you don't
have direct hardware knowledge & control.
Especially in virtual world you often get already some 'provisioned' space
which nowhere near to anything physical. Try to stripe such drives makes
no practical sense.
Regard
Zdenek
