xoa slow export speed - peak 30MB/s

akurzawa

Hi

I'm testing latest xoa - with xcp 8.x (latest) and 7.6 and the export speed of vm is at max 30MB/s on idle 1Gb network.

I've observed on the performance chart that then exporting vms the xoa vm uses one cpu per export, also the ram was maxed out. Is there a way to use multiple cpu when exporting vms to increase export speed? i know this is not trivial, but I just wanted to know if there is something that can be done to increase export speed. Under the hood there is local storage raid 10 (perc h700) with about 350MB/s read write performance. No changes when I used SSD as local storage. Still cap circa 30MB/s. What is the cause of that? If I will want to export 2TB vm i will wait for 19 hours... assuming constant 30MB/s export which is a wish becouse the export speed drops to few mb/s regularly.

hardware: dell r510 v1/v2
nics: 4port Intel Corporation 82576
Broadcom Limited NetXtreme II BCM5716 Gigabit - and the management is on this broadcom, BUT I've tested the export also on the intel NIC - no chages.

I have a question to everyone: what were your best export speed and what storage and network do you have ?
How does it look on 10Gb network?

olivierlambert

What kind of export are you using? XVA? compression enabled or not?

akurzawa

@olivierlambert I've tested all types. Albo connecting servers as http. I don't know what can I expect. So I'm asking the others to compare results.

olivierlambert

Do you have power settings to "Performance" in your host BIOS?

akurzawa

I've tested this in last year - no difference in vm performance, I've leaved it on controlled by OS.

olivierlambert

Can you put it in performance and redo the export please?

akurzawa

Hi

I have the results from another host - dell r410 but the setup is the same (perc h700, local storage, 2x xeon, 128 ram, xcp 8.2)

The export speed is almost identical about 30MB/s however the import was almost twice that fast - almost 60MB/s so this is curious.

Export:

Import:

and despite only 2cpu and 2gb ram (default for xoa) vs 8cpu 8gb ram I don't see cpu hitting the 100%. The results from 1st post are from xo located on xcp 7.6, those are from xoa located on the xcp 8.2 host.

Setting were set to max performance:

olivierlambert

It's not curious. Generating an XVA is using a ~~fucked up~~ weird algorithm. That's why it takes time. Exporting a VHD will be faster (that's also why even full VHD export is faster than XVA export).

akurzawa

@olivierlambert ok so - I have 48 CPU cores - any chance to make the algoritm multithread?

olivierlambert

Personally, I wouldn't touch anything regarding XVA generation, it's deep into XAPI code.

Rely on delta backup in general, it's better.