[OpenAFS] Is OpenAFS for me?

Lars Schimmer l.schimmer@cgv.tugraz.at
Tue, 07 Mar 2006 16:05:05 +0100

Hash: SHA1

Karl Bellve wrote:
> Sorry if this has been answered but after several days trying to narrow
> down to a dristributed filesystem, I am still unsure what to pick. I
> have narrowed it down to two: OpenAFS, and GFS.
> Here is what I need:
> 1) Automatic data replication to multiple computers each with a drive
> dedicated to the OpenAFS volume. If one computer goes down, the data is
> still available from another computer.

Automatic file replication is not available in OpenAFS.
Just the method of cloning/releasing a volume to a readonly volume by
hand OR script.

>   1a)  I plan on having 10 to 15 computers exporting one 400-500GB
> drive..How many drives/computers can I lose without jeopardizing the
> OpenAFS volume?

The volume itself is on the partition it is created on. If you put the
readonly copies of the volume to x other fileservers, you can shutdown x
server maximum and there is still one server with the volume available.

>    2a) What happens to the OpenAFS system if I have to bring all the
> computers down, one by one?

Until the last database server and/or fileserver is down it still works.
After all are down, the system is down, to. But not damaged, just down.

> 2) Expandable. Can I add another 400-500GB drive to a new computer and
> add it to an existing OpenAFS volume?

No, just if you use RAID and/or LVM2.

> 3) Does OpenAFS need RAID for redundancy or is it taken care of at the
> filesystem layer?

Redundancy of data is taken care of by the filesystem with the
rw/readonly volumes.
But there is always the possibility to add extra redundancy with a RAID.

> 4) Is there a 2GB file limitation? (I have read conflicting reports)

Yes, in older versions prior to 1.4.0 there was a 2 GB file limit. And
in the windows client there is the practical limit of 2GB/file because
of the usage of the windows CIFS protocol. OpenAFS itself can handle
files larger than 2 GB.

Lars Schimmer
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