[Linux-cluster] IMAP server clustering ...

[David B Zafman]

See www.drbd.org

What is DRBD
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DRBD is a block device which is designed to build high availability 
clusters. This is done by mirroring a whole block device via (a 
dedicated) network. You could see it as a network raid-1.

On Nov 1, 2004, at 10:59 AM, linux-cluster at spam.dragonhold.org wrote:

> On Mon, Nov 01, 2004 at 11:26:07AM -0700, Michael Gale wrote:
>>
>> That makes more sense ... thanks for the info and in helping me avoid
>> corrupted data.
>>
>> Michael.
>>
>
> No worries - I have the best possible reason for remembering, that of 
> personal experience.
>
> I managed to miss that a partition was mounted on a solaris box 
> (through veritas), and
> therefore mounted it again manually (raw partition) somewhere else - 
> the behaviour was
> "interesting" until it got so bad I rebooted.
>
> I ended up having to restore from the backup, which is why I remember 
> it so vividly - we had
> never tested the backups until then.
>
>
> You've got me thinking tho.  Depending on how much of the caching is 
> done in the filesystem
> layer, and how much at the block device layer, it /might/ be possible 
> to create a cluster
> aware block device, and then use a normal FS on top of it.
>
> Anyone around know enough to tell me how possible/not that would be?
>
> If it was possible, it should be possible to implement things like 
> mirroring & snapshots at
> that level more easily than trying to do them higher up the chain.
>
> However, that may just be total baloney, since I've not really thought 
> it through - one of
> those "I wonder" ideas that I don't know enough about at the moment to 
> investigate.
>
> Graham
>
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>
>
David B. Zafman                             | Hewlett-Packard Company
mailto:david.zafman at hp.com     | http://www.hp.com
"Computer Science" is no more about computers than astronomy is about 
telescopes                                            - E. W. Dijkstra