libvirt users - Oct 2021 - how can i measure reliably the speed of a virtual disk ?

Hi,

we have some domains running on a two-node pacemaker cluster. The disks for the
domains are raw files
which reside on a SAN.
I measured the speed of one domain inside the guest and got completely weird
results:
between 18MB/s and 750MB/s !?!

I measured with hdparm -t.
I think this is related because, from the host point of view, some data is on
the disk and some data is on chache.
The -t i used for hdparm does not influence the host, just the guest.

Measures on the host give reliable and reasonable results about 350 MByte/s.

How can i measure reliably the speed of a virtual disk ?

Bernd

-- 

Bernd Lentes 
System Administrator 
Institute for Metabolism and Cell Death (MCD) 
Building 25 - office 122 
HelmholtzZentrum M?nchen 
bernd.lentes at helmholtz-muenchen.de 
phone: +49 89 3187 1241 
phone: +49 89 3187 3827 
fax: +49 89 3187 2294 
http://www.helmholtz-muenchen.de/mcd 


Public key: 

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