[OpenAFS] Howto speedup the restore of a crashed fileserver

Jose Calhariz jose.calhariz@tagus.ist.utl.pt
Tue, 2 Oct 2007 17:13:02 +0100

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On Tue, Oct 02, 2007 at 08:23:03AM -0500, Christopher D. Clausen wrote:
> Jason Edgecombe <jason@rampaginggeek.com> wrote:
> > Jose Calhariz wrote:
> >>> If you're not already, I recommend restoring into a local directory,
> >>> then copying into AFS. That will at least make the tape part go
> >>> faster and reduce wear and tear on the tapes and drive.
> >>>
> >>
> >> I am doing that,  As I can recover from tapes faster than I can
> >> write to AFS.  Specially because I use virtual tapes on disks.
> >>
> > Do you have multiple AFS servers? If so, are you copying files to
> > different servers simultaneously? Perhaps it's worthwhile to set up a
> > temporary server and then do a "vos move" of the volumes after
> > everything has settled.
> What are the settings on the client you are using to restore the files=20
> into AFS?  I'd suggest maybe using a memcache while doing restores.=20
> Should avoid needing to write the data into the AFS cache file.=20
> Additionally, is the AFS cache file on the same block device as your=20
> vice partitions?  Keeping things on seperate physical disks should
> help.

The /vicep partitions are on RAID5 by hardware, different from the
system disks that are two independent disks on RAID1 by software.

I have tried memcache, it's faster, tried to setup a disc cache on a
tmpfs filesystems, seams to be better.  But I don't know to tune a
disc cache on tmpfs.  To be correct the disc cache is on a file with a
ext2 filesystem, that is stored on a tmpfs, with a size of 25% of the
RAM on the server.

Other very important factor is the load the clients have over the
production servers file servers.  The speed of recovery on the night
is like 10 times faster than on the day.

I will setup an extra file server to speed the recovery.

> <<CDC=20

    Jos=E9 Calhariz

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