[OpenAFS] Re: [OpenAFS-devel] 1.6 and post-1.6 OpenAFS branch management and schedule

Steven Jenkins steven.jenkins@gmail.com
Wed, 16 Jun 2010 08:43:39 -0400

On Wed, Jun 16, 2010 at 6:07 AM, Hartmut Reuter <reuter@rzg.mpg.de> wrote:
> Without --enable-fast-restart after a fileserver crash the salvager used to
> salvage all volumes in all partitions before the start of the fileserver.
> On large fileservers this could take hours and sometimes the salvager went out
> of memory and crashed himself leaving still volumes not attachable.
> With the Demand Attach Fileserver (DAFS) this initial salvage is not necessary
> any more, however, each volume which was not cleanly detached before gets
> salvaged in the background. This is a nice feature which allows the most
> demanded volumes to come up soonly, I hope, but still salvaging will take hours
> because it's the same amount of work that has to be done.

Keep in mind that DAFS never brings volumes online unless requested by
a client, so some volumes may never be attached; it also takes volumes
offline after a period of unuse, so a DAFS server will only need to
salvage the 'active' volumes after a crash.  The combination of those
two features greatly reduces the number of volumes to salvage, so it's
not actually doing the same amount of salvaging (in the general case)
as a traditional fileserver.