Re: Help!About MD on shared storage.

[David Chow <davidchow@shaolinmicro.com>]

>
>
>Note that the same thing can be done using a configuration file per node
>and using mdadm to only start the RAID volumes needed.  This is the
>methodology recommended by RAID maintainer, Neil Brown, however, I find
>it difficult to setup which is why I proposed the patch.  He could
>probably provide more info on that methodology or there is a discussion
>in the archives.
>
>If I ever get some time, I plan to implement shared access to the same
>RAID volume for usage in a clustered filesystem application such as GFS.
>
If it really happens, every writes to the RAID will need to be synced . 
Since fs assumes the underlying block device is synced instead of async 
like md . This has been an issue of using md on cluster environment 
which calling sync only sync fs->block buffers and md buffers are not 
gaurantee to be synced. I am not sure how much performnace drawback will 
cause if every write to md must be synced and wait for return for the 
underlying real block device. Any ideas?

David