Re: Hardware vs. Software RAID
- From: "Mark Brinsmead" <pythianbrinsmead@xxxxxxxxx>
- To: david@xxxxxxxxx
- Date: Sun, 6 May 2007 20:58:43 -0600
Wow. Software RAID. People still use that?
Seriously, its usually not too hard to justify the cost of pushing the RAID
logic into the hardware layer.
Software RAID can consume a lot of CPU cycles. And if you happen to be
running EE, you've likely paid anywhere from $40K to $90K (depending on
features) per CPU to get those cycles. Not wasting CPU cycles on something
that is better done in the hardware seems to be a no-brainer in this
context.
In addition to saving expensive CPU cycles, hardware raid permits (can
permit) the use of write caches. (Caching writes with software raid
requires non-volatile memory; specialized hardware.) Hardware RAID can
increase the effective transfer rate between the database server and the
disks by a factor of 2 or more. And it can be extremely cheap.
Software RAID is (probably) better than no RAID at all. But I would never
use it by choice. Nor to save $10k.
If your application is not sufficiently important to warrant the "extra
cost" of hardware RAID, how do you justify the "extra cost" of using RAID at
all?
Heck, if cost is the primary consideration, you can deploy all the storage
you'll ever need (including more than 2000% room for future growth) with a
single ATA disk drive costing about $200... Why do I have the feeling that
whoever has asked you to cost-justify hardware RAID is next going to demand
a cost justification for backups? :-)
Seriously, though, hardware RAID offers numerous benefits. It should be
easy to justify. But then, I have seen some pretty strange decision-making
processes in my travels...
As for "collateral" to back you up -- why not start with the storage
vendor? If they cannot help you justify this purchase, they don't deserve
to make the sale!
On 5/3/07, David Peasley <david@xxxxxxxxx> wrote:
Hi all,
I'm being asked to justify the cost of hardware over software raid (38
gig Oracle 9.2.0.6 database, soon to be migrating to 10g - on Solaris).
Does anybody know of any good white papers, benchmark tests, etc., that
you could point me to? Or, any opposing opinions - I can take that
too. :)
...
--
//www.freelists.org/webpage/oracle-l
--
Cheers,
-- Mark Brinsmead
Senior DBA,
The Pythian Group
http://www.pythian.com/blogs
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