more samsung ssd woes

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zedicus

Renowned Member
Mar 5, 2014
26
4
68
CPU BOGOMIPS: 67194.56
REGEX/SECOND: 1968961
HD SIZE: 881.38 GB (rpool/ROOT/pve-1)
FSYNCS/SECOND: 1203.74
DNS EXT: 20.35 ms
DNS INT: 21.52 ms (subliminal.local)


pair of 860 evos in raidz mirror 1gb drives
this is the rpool and i was hoping to share it with VM's but not with those speeds

atop shows 2% on the disks
ashift is 12
scheduler is noop

server has 64gb ram
ZFS is limited to 8gb

can this be made tolerable or do i need to toss more $ at it?
 
Hi,

this is for a Samsung EVO not bad.
What do you think you get and why can't you use it for the VM too?

But anyway for a real test you should use FIO.

Code: 
fio --filename=/rpool/data/fiotest.fio --bs=[4k|128k} --rw=[read|write] --name=test --direct=[0|1] --sync=[1|0] --size=10G --numjobs=1
 
i will try that today.

i have a small old raid 5 array in my old server that gets 3300 fsyncs. i figured a pair of ssd even zfs would be way faster. guess i should have done my math instead of just assuming.
 
This comparison is not valid because your raid must use a cache what is normally an SDRAM.
SDRAM is at the moment faster than VNAND.
Also, the Samsung 860 EVO is a consumer SSD and not an enterprise-class SSD with high sync capability.
If you what increase you sync performance you can add a ZIL device like the Intel optane memory.
 
if i added an nvme zill what type of increase in fsync do you think i would be getting?
 
zedicus said:
if i added an nvme zill what type of increase in fsync do you think i would be getting?
Click to expand...
That depends in the end on the type of workload your VMs will produce. But the reviews on the Intel Optane show a good 4k seq write.
 
mostly data storage but there is 2 web portals hosted and 1 shared mysql database. and the typical DC and windows VMs for virtual desktops. only about 5 of those though.

and i push backups regularly so for the main VM store i am more interested in performance, it is on a zfs mirror just as a 'can't hurt' scenario.

would a 16gb optane be enough for the slog from the 1tb mirror or would a 32gb optane be best?

thanks for the help.
 
zedicus said:
would a 16gb optane be enough for the slog from the 1tb mirror or would a 32gb optane be best?
Click to expand...
If you have the choice of those two, then why not just go for the bigger?
 
actually based on IOPS i am looking at going with the 58gb.
it is substantially faster for not much more coin.
 
would it be worth reloading proxmox onto the optane and setting up a 32gb partition for SLOG and JUST hosting VMs off the SSD zfs mirror?
 
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