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Ariyo Nugroho wrote:
> I'm going to do it with databases. From the HOWTO, it's said that
> implementing such configuration needs distributed filesystem.
The HOWTO says that you need someway of distributing the writes to all
the realservers. This can be done at the application level or at
the filesystem lever. At the time we first considered running
databases on LVS, neither distibuted filesystems nor replication
was easily available on Linux. Pushing writes would have to
be done via a DBI/DBD interface or similar. I expected that distributed
filesystems were just around the corner (intermezzo, CODA), but
they never arrived. In the meantime mysql has implemented
replication and pushing the writes now seems best done at
the application level.
Ratz in his postings to the mailing
list has shown how most problems that involve maintaining
state across the realservers can and should be solved
at the application level. It only seems reasonable
to approach the database write problem the same way.
If someone comes up with a bulletproof, easy to maintain,
reliable distributed filesystem, then all of this will be thrown
out the window and we'll all go to distributed filesystems.
However with the effort that's been put into distributed filesystems
and the lack of progress that's been made, relative to the
progress from modifying the application, I think it's going to
be a while before anyone has another go at distributed filesystems
for Linux.
I'm sure the HOWTO says that LVS databases can use distributed
filesystems. However LVS'ed databases don't require (==need)
distributed filesystems. If I've said otherwise in the HOWTO
please let me know and I'll fix it.
Joe
--
Joseph Mack PhD, High Performance Computing & Scientific Visualization
SAIC, Supporting the EPA Research Triangle Park, NC 919-541-0007
Federal Contact - John B. Smith 919-541-1087 - smith.johnb@xxxxxxx
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