[linux-lvm] LVM2 resync speed problems

[Leonard Smith]

Forgot to mention, the drives are WD 500 GB "Raid enabled" SATA
drives. They are some of WD newer drives, and I think they are
techincally SATA2. The other system also has the same drives.


On 6/13/07, Matthew Gillen <me at mattgillen.net> wrote:
> Leonard Smith wrote:
> > I am running CentOS4.4 on  two "black" box systems that are
> > identically configured. Both have 500 GB internal drives, ( same type)
> > and were installed using the same kickstart configuration. The drives
> > are being mirrored using LVM.
> >
> > When I check the first system it is re-syncing and the resync time and
> > speed are
> >
> > finish=18559.6min speed=355K/sec
> >
> > On the second system the time and speed are
> >
> > finish=89.5min speed=68170K/sec
> >
> > I can't figure out why the speeds are different between the two. I
> > checked /proc/sys/dev/raid/speed_limit_ and they are the same. The
> > priority of the md proceses are they same.
> >
> > I tweaked the setting of the speel_limit_min and increase the nice
> > priority of the resync process, on the first box, but I could never
> > get it better than
> >
> > finish=4551.8min speed=1445K/sec
> >
> >
> > I've googled and I haven't found much more useful information that to
> > adjust those settings. Besides those setting what else dictates the
> > speed used?
>
> You might compare the hd settings using 'hdparm'.  I'm not sure factor of 100+
> can be explained by an incorrect DMA setting or something like that, but it
> might be a contributor.
>
> Matt
>
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