Re: [Xen-API] [XCP 1.6 beta] poor performance while importing vm template

[SÃbastien RICCIO <sr@xxxxxxxxxxxxxxx>]

Hi,

On 03.10.2012 09:32, SpamMePlease PleasePlease wrote:
> > Have you tried basic disk read or write throughput tests on these disks like
> > running a:
> > dd if=/dev/zero of=test bs=1M count=2000 oflag=direct
> While doing so, the io wait also skyrockets (up to ~60%), along with
> load average (up to ~2), with the average speed of 12,8 MB/s. However,
> the hdparm reports as below:
That is very slow write performance for 1megs blocks. Doing the same 
test on dell box here (with 500mb because i have not enough free space 
to do the 2gig test)
[root@xen-blade11 tmp]# dd if=/dev/zero of=test bs=1M count=500 
oflag=direct
500+0 records in
500+0 records out
524288000 bytes (524 MB) copied, 2.08047 seconds, 252 MB/s

That might be where you should start investigating. Does your controller 
has write-back enabled (instead of write-through) ?
> /dev/sda:
>   Timing cached reads:   23680 MB in  1.99 seconds = 11887.43 MB/sec
>   Timing buffered disk reads: 492 MB in  3.01 seconds = 163.45 MB/sec
That is caching reads test, this is kinda irrelevant for large data 
transfers.
I might be wrong but for me you have an issue with write throughput.

Cheers,
SÃbastien



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