[Xapian-discuss] Xapian across multiple servers

[Rob S]

On Thu, Jul 24, 2008 at 6:11 AM, Olly Betts <olly at survex.com> wrote:
> On Wed, Jul 23, 2008 at 03:27:08PM +0100, James Aylett wrote:
>> On Wed, Jul 23, 2008 at 04:08:12AM +0100, Olly Betts wrote:
>>
>> > The NFS caching issue is rather relevant to admins, especially if the
>> > cache gets flushed even for the client modifying the database (as that
>> > would mean putting the database on NAS isn't good).
>>
>> Does anyone have any knowledge of the serious NAS FSs in this respect?
>> I believe AFS provides partial updates, and it's possible you can do
>> similar things with SAM-FS (does that have a distributed version?).
>
> I don't know about specifics, but indeed this isn't an inherent
> limitation of the approach.
>
>> There are probably also tricks you can do on linux with block-level
>> replication out of DRBD.
>
> The "SAN" approach to remote storage should be much easier for the OS to
> cache.
>

Maybe I've misunderstood something, but I'm not sure that SAN makes
any difference.  SAN just moves the point at which the network is
involved:

NAS:    Server-with-disks-in-running-a-filesystem -> network
SAN:    disks -> server-running-filesystem -> network

Of course the diagram at
http://en.wikipedia.org/wiki/Image:SANvsNAS.svg is a lot better.

So, the problem of the clients sensibly caching is a property of the
network file system, not of the underlying architecture.


> Cheers,
>    Olly
>
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