[Linux-cluster] ext3 filesystem

[Robert Peterson]

Herta Van den Eynde wrote:
> On 14/12/06, Robert Peterson <rpeterso at redhat.com> wrote:
>> David J. Otis wrote:
>> > Is it possible to have an ext3 filesystem mixed with the gfs
>> > filesystems on my SAN that can be mounted by all nodes?
>> Hi David,
>>
>> As long as the ext3 file system is mounted read only by all but one
>> node, you should be able to do this.
>> However, if you need read/write capabilities on both file systems on the
>> SAN, then ext3
>> will just get you in trouble.  Since ext3 isn't cluster aware, the nodes
>> will walk all over each other's data.
>> That's what GFS was designed to prevent.
>>
>> Regards,
>>
>> Bob Peterson
>> Red Hat Cluster Suite
>>
>
> What good is mounting the ext3 filesystem read-only on all but one node?
> Suppose node A is the node that mounts the filesystem read-write, and
> node B a node that mounts it read-only.  B reads a file from the
> filesystem, which gets cached on node B.  Node A changes that same
> file.  How is node B to know that the data it cached is out of date?
>
> Kind regard,
>
> Herta
Herta,

You're right--the other nodes won't be informed of file system changes,
so they should all mount ext3 read-only.  Better to use GFS.

Bob Peterson
Red Hat Cluster Suite