[OpenAFS] Re: about replica

[Martin Schulz]

"Boris H." <boris@openow.net> writes:

> I wanted to use AFS storage my all data, including mySQL data, and Oracle data. And the data is always changing.

I think it is a bad idea to load database files in AFS. 

- its relatively slow (network connection!). 

- AFS is a distributed filesystem, the database can only run on
a single machine 

-  if you need a distributed database use one 

- AFS consistency is guarantied upon the closure of a file, but a
database keeps its files open virtually all the time.

> Because I worry about the data losing, I want to use multiple RW
> replicas. Even if the master volume occur errors, the other replicas
> could support my application automaticly. Since OpenAFS does not
> support multiple RW replicas, do you have the other good idea about
> my requirements?

What kind of errors do you fear in the master volume? How do you tell
if a volume might suffer from a silent data corruption?

If you do not trust your hard disc manufacturer, go for a proper raid
in your database server. If you fear a fire in your server room, some
scsi-over-ip thing (or something else) might help you to locate the
discs in different locations. A properly distributed database is
probably the better idea.

Don't get me wrong: I thing AFS is good for what it's made for, but
not for database files IMHO.

Yours,
-- 
Martin Schulz                             schulz@iwrmm.math.uni-karlsruhe.de
Uni Karlsruhe, Institut f. wissenschaftliches Rechnen u. math. Modellbildung
Engesser Str. 6, 76128 Karlsruhe