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On Tue, 16 Jun 2009 15:58:37 +0200 |
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Philipp Riegger <lists@××××××××××××.de> wrote: |
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> |
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> On Tue, 2009-06-16 at 16:45 +0300, Daniel Iliev wrote: |
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> > DRBD is HA solution which is achieved by switching the role of the |
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> > nodes in case the "active node" goes offline. I think DRBD is not |
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> > meant for the schema OP has described, because only the "active |
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> > node" is accessible via FS. DRBD works between the FS and block |
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> > device layers. It catches the FS writes from the active node and |
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> > sends them over the network. DRBD on the backup node receives those |
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> > and replicates them directly to the disk driver. Thus you can't |
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> > have mounted FS on the backup node. If the active node goes |
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> > offline, the backup node takes over which means DRBD switches roles |
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> > and the FS has to be mounted afterwards. |
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> |
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> But that might be a good solution with 2.6.30, NFS and FSCACHE. |
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> |
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Sorry, perhaps I'm missing something, but I couldn't understand |
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the solution you had in mind. |
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I'm just saying that the only scenario I have some experience with is |
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DRBD + ext3 and it won't work for load balancing. |
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If "LAMP A" and "LAMP B" as shown on the OP's schema were connected via |
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DRBD + a conventional FS (ext/xfs/reiser/etc.), then only one of those |
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systems would be able to serve client requests at a given moment. |
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-- |
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Best regards, |
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Daniel |
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