Mount same ext3 filesystem in 2 places... at the sametime

[Robert Brockway]

On Wed, 30 Sep 2009, Anton Verevkin wrote:

> But this is exactly the case when computers do not recognize that they 
> are not alone using this partition. Though SCSI bus (and Fibre Channel 
> as its successor) do handle the situation of simultaneous access to disk 
> and have disk locking procedures, operating systems were not aware of 
> changes made by another computer and I had to clear disk cache to see 
> the changes made by another system. And of course simultaneous write 
> could damage the data.

Hi Anton.  What you need is a "clustered filesystem".  This is a 
filesystem that is aware that it will be written to by multiple directly 
connected systems.  Without a clustered filesystem writes will sooner or 
later cause filesystem corruption as you note.

To do this cross-plaform you will need to find a clustered filesystem that 
is supported by all of the OSes you want to use.  They do exist but not 
necessarily as OSS.

> I guess there might be some tools to teach the operating system to work 
> in a team with other computers, and most probably this will turn to 
> something like ZFS. But anyway we should always be very careful with 
> these matters.

ZFS is not a clustered filesystem (yet).   Developing a clustered 
filesystem is a very complex proposition so I don't blame Sun for waiting 
until the non-clustered version is nice and stable.  OpenSolaris offers 
the QFS clustered filesystem.

Cheers,

Rob

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