Re: [Xen-users] RAID-1 strategy for a Xen/CentOS server?
FWIW, "this box" has 4GB RAM atm, expandale to 8GB.
IMHO that means nothing... if it's handling 4 mailboxes, it's overkill, if
it's handling 40,000 you're probably dead before you even started... but
then you could come up with particular examples where the roles of that 4
and 40,000 could be reversed... e.g. support@xxxxxxxxxxxxx,
abuse@xxxxxxxxxxx, etc versus 40,000 never used freebie accounts that are
included with some other product...
"If you are using RAID-1 to help to ensure that your system stays up in the
event of a hard disk partition failure, you should consider raiding your
No argument. Generally my thinking with respect to raid 1 is to reduce the
chance of data loss, but as per the introductory clause, there can
be different goals.
My broad-brushstroke goals -- for the whole system,as well as for individual
DomUs -- include:
(1) Maximize failover capability
??? By definition, "failover" requires redundant hardware, sort of the
opposite of cutting up a big machine into smaller pieces (xen). If you
want failover capability, see linux-ha.org ... and you need to be able to
get at the data from the redundant hardware... it's a rather different
picture than a normal server setup.
Stuffing DRBD under the vbd's so that a redundant server can mirror the
block devices is fine start :) ... but that certainly isn't what I thought
you meant by hardware vs software RAID... and you're entering the world of
network attached storage....
(2) Minimize potential fordata loss due to HW failure
(3) Maximize the performance of the system
(I've given up on running at less than 10W total power utilization ... ;-) )
You're correct -- in answering my misstated question. I *meant* to ask:
What's the recommended FS for the Dom0 Xen host?
it is basically irrelevent, as anything that will boot xen is pretty much
sufficient. dom0 isn't supposed to do much work (beyond having the kernel
relay I/O requests to the real hardware). If you're using file images
instead of block devices for your domU vbd's then it may be relevent...
but ext3 should be fine. I can't really imagine a scenario where the more
esoteric filesystems would be needed... but I'm no expert, and when you
get into journalling filesystems (in the domUs) there are some complex
interactions (e.g. preserving the order of writes, which is one reason why
using real block devices instead of files may be better).
(Then again, using disk files for filesystem images probably conflicts
with maximizing failover capabilities... this may depend on how many domUs
you have, and whether you need/want to be able to fail them over
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