On Tue, Feb 24, 2009 at 5:21 PM, Jordan Tomkinson <jordan@moodle.com> wrote:
>
> On Wed, Feb 25, 2009 at 12:05 AM, Aidan Van Dyk <aidan@highrise.ca> wrote:
>>
>> * Greg Smith <gsmith@gregsmith.com> [090201 00:00]:
>>
>> > Shouldn't someone have ranted about RAID-5 by this point in the thread?
>>
>> What? Sorry, I wasn't paying attention...
>>
>> You mean someone's actually still using RAID-5?
>>
>> ;-)
>
> What exactly is wrong with RAID5 and what should we have gone with?
RAID 5 is only suitable for situations where you need maximum storage
for minimum cost and the database is mostly / all read all the time.
Like large reporting databases. It's slow on writes, and it has a low
tolerance for dead drives (2 and it's all gone)
HOWEVER. RAID-10, which is theoretically MUCH better, is only better
if it's implemented right, and lot of cheap RAID controllers don't do
any better running RAID-10. Many of these can be put into JBOD mode
where you do RAID-10 in the kernel, or you can do RAID-1 on the card
(x sets) And RAID-0 in the kernel.
RAID-10 is almost always the right choice when you're buying good
controllers and fast drives and you want maximum performance. If you
REALLY need a lot of storage, and you have to use something like RAID
5 at least look at RAID 6.