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On Wed 22 Jun 2005 08:36:37 BST , Gavin Henry
<ghenry@xxxxxxxxxxxxxxxxxx> wrote:
What do people recommend for shared storage for the realservers and
directors?
Why would you want shared storage for the directors? [this isn't a
"what a dumb idea" question, I just don't understand why you'd need
it...]
If you were to link the directors together in some way, assuming that
you run them in a MASTER/BACKUP system, having something gluing the two
together would (in my mind) quite effectively negate the redundancy
capability and turn the two of them into a SPOF. Unless I misunderstand
you :)
Someone recommended drbd for the directors, but what about the real servers?
NAS/SAN?
The configuration we are planning to implement is a dual director setup
with 3 realservers for apache.
Assuming this is Apache on Linux (or other UNIX) then cost is your
biggest hurdle, followed by performance. For a toe-in-the-water test,
use vmstat or sar on a current server and collect a few days' data
regarding disk IO. You can then work out how many concurrent read/write
ops you utilise, and work out the relevant peaks & averages - but note
that compared to disks in servers it would differ slightly for NAS or
SAN operations due to the way they're built. It would give you an idea,
at least.
Then you can look at what's on the market.
Probably the most mature shared storage platform for Linux would be a
NAS doing NFS; the most experience I have of this is a Network
Appliance filer but they aren't cheap.
I've no experience of NAS usage under Linux, so can't comment on that
directly.
Perhaps you could use a shared DAS instead, like the HP storage arrays?
HTH
Graeme
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