[OpenAFS] 'replication'

[Hartmut Reuter]

Rubino Gei=DF wrote:
--snip--
>=20
> Anyway, does anyone know a setup or trick to make a RO volume a RW
> volume?
>=20
> Some time ago there was a reference to some "admin hack" or something
> like that on this list, but nothing more. I'd like to regularly do vos
> releases on a set of volumes and in case of disaster switch to the RO a=
s
> RW volumes... is possible or do we have to "hack" openAFS for that? -- =
I
> know backups do the trick (of some kind of disaster recovery; and we do=

> daily  backups), but restoring > 100GB will cause significant outage!

We have a similar backup strategy: the user's home volumes are=20
replicated in their own partition and into a partition on another cheap=20
big server. "vos release" runs each night.

Whenever the original partition should break I will do a
"vos convert <otherserver> <partition> <volume>"
which converts the RO into a RW-volume.

This "vos convert" command, however, is an extension I wrote for MR-AFS, =

but suppose it could easily be implemented for OpenAFS with=20
NAMEI-interface as well. practically it only does things:

1) it checks the vldb and prompts for a yes if the RW-volume exists at=20
another place.
2) it checks only one volume is in the volume group on this partition.
3) it renames the large and small vnode-files in the special directory=20
and creates a new volinfo special file with the correct volume id and nam=
e.
4.) it removes the old volinfo file and volume header file and create a=20
new volume header-file.
5.) it updates the vldb-entry to point to this RW.

This command is pretty fast. You could regain the volumes of a 200 GB=20
partition in half an hour. Much faster than to restore the contents from =

tapes.

Hartmut

>=20
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--=20
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Hartmut Reuter                           e-mail reuter@rzg.mpg.de
					   phone +49-89-3299-1328
RZG (Rechenzentrum Garching)               fax   +49-89-3299-1301
Computing Center of the Max-Planck-Gesellschaft (MPG) and the
Institut fuer Plasmaphysik (IPP)
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