I think RAID 10 is best among all the RAID Levels.
Thanks
Craig Ringer wrote:
On 04/08/11 11:42, Jayadevan M wrote:
Hello,
>The most important spec has been omitted. What's the storage
subsystem?
We have storage on SAN, RAID 5.
RAID 5? That's *really* not ideal for database workloads, either Pg or
Oracle, unless your RAID 5 storage backend has enough battery-backed
write cache to keep huge amounts of writes in RAM and reorder them
really effectively.
I hope each RAID 5 LUN is only across a few disks and is layered with
RAID 1, though. RAID 5 becomes less reliable than using a single disk
when used with too many HDDs, because the probability of a double-disk
failure becomes greater than that of a single standalone disk failing.
After being bitten by that a few times, these days I'm using RAID 6 in
most cases where RAID 10 isn't practical.
In any case, "SAN" can be anything from a Linux box running an iSCSI
target on top of a RAID 5 `md' software RAID volume on four 5400RPM
HDDs, right up to a giant hundreds-of-fast-disks monster filer full of
dedicated ASICs and great gobs of battery backed write cache DRAM. Are
you able to be any more specific about what you're dealing with?
> > We are suing weblogic.
> ^^^^^
> Best. Typo. Ever.
>
> I hear most people who use it want to, you're just brave enough to
do it :-P
I wish I could make a few millions that way.
Thank you for all the replies. The first step is, of course,
to migrate the data. I am working with ora2pg for that. I assume
creating files with 'COPY' to work as input for PostgreSQL is the right
approach? We don't have many stored procedures or packages. So that
part should be OK.
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