High fsyncs/sec and high IO wait

[did-vmonroig]

Hi all,

I'm testing a new setup with ZFS: Two mirrored SATA 1TB magnetic drives and a 120GB SSD drive for ZIL + L2ARC.

This are pveperf results:

root@servidor01:~# pveperf 
CPU BOGOMIPS:      24744.08
REGEX/SECOND:      2625273
HD SIZE:           377.89 GB (rpool/ROOT/pve-1)
FSYNCS/SECOND:     26506.76
DNS EXT:           2002.57 ms
DNS INT:           2002.25 ms (oficina.domain.tld)

This seems a pretty good fsyncs/second number, nevertheless IO wait is very high during boot and Windows upgrade process:



Is this normal? Should I expect better IO wait?

Thank you!

 

[manu]

I/O wait means here that the hard disk is the bottleneck of the current activity of your system.
During boot and upgrade the cpu doesn't have much to do, but the hard disk has a lot to do, so its normal in that case that the limiting factor is the hard disk.

 

[did-vmonroig]

Thanks, manu.

I thought that IO wait was never going to be so high, as fsyncs are so good.