Your example would prove more effective if you added, "I've got ten
databases. Five on AIX, Five on Solaris 8...."
Peter Rival wrote:
I don't like to top-post, but there's no better way right now. This
issue has recurred several times and there have been no answers to it
that cover the bases. The question is, say I as a customer have a
database, let's say it's around 8 TB, all built on a series of high
end storage arrays that _don't_ support the JBOD everyone seems to
want - what is the preferred configuration for my storage arrays to
present LUNs to the OS for ZFS to consume?
Let's say our choices are RAID0, RAID1, RAID0+1 (or 1+0) and RAID5 -
that spans the breadth of about as good as it gets. What should I as
a customer do? Should I create RAID0 sets and let ZFS self-heal via
its own mirroring or RAIDZ when a disk blows in the set? Should I use
RAID1 and eat the disk space used? RAID5 and be thankful I have a
large write cache - and then which type of ZFS pool should I create
over it?
See, telling folks "you should just use JBOD" when they don't have
JBOD and have invested millions to get to state they're in where
they're efficiently utilizing their storage via a SAN infrastructure
is just plain one big waste of everyone's time. Shouting down the
advantages of storage arrays with the same arguments over and over
without providing an answer to the customer problem doesn't do anyone
any good. So. I'll restate the question. I have a 10TB database
that's spread over 20 storage arrays that I'd like to migrate to ZFS.
How should I configure the storage array? Let's at least get that
conversation moving...
- Pete
Gregory Shaw wrote:
Yes, but the idea of using software raid on a large server doesn't
make sense in modern systems. If you've got a large database server
that runs a large oracle instance, using CPU cycles for RAID is
counter productive. Add to that the need to manage the hardware
directly (drive microcode, drive brownouts/restarts, etc.) and the
idea of using JBOD in modern systems starts to lose value in a big way.
You will detect any corruption when doing a scrub. It's not
end-to-end, but it's no worse than today with VxVM.
On Jun 26, 2006, at 6:09 PM, Nathanael Burton wrote:
If you've got hardware raid-5, why not just run
regular (non-raid)
pools on top of the raid-5?
I wouldn't go back to JBOD. Hardware arrays offer a
number of
advantages to JBOD:
- disk microcode management
- optimized access to storage
- large write caches
- RAID computation can be done in specialized
d hardware
- SAN-based hardware products allow sharing of
f storage among
multiple hosts. This allows storage to be utilized
more effectively.
I'm a little confused by the first poster's message as well, but you
lose some benefits of ZFS if you don't create your pools with either
RAID1 or RAIDZ, such as data corruption detection. The array isn't
going to detect that because all it knows about are blocks.
-Nate
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