[CentOS] Re: RAID5 or RAID50 for database?
Scott Silva
ssilva at sgvwater.com
Thu May 22 17:16:31 UTC 2008
on 5-22-2008 9:12 AM Rudi Ahlers spake the following:
> Warren Young wrote:
>> John R Pierce wrote:
>>> raid50 requires 2 or more raid 5 volumes.
>>>
>>> with 4 disks, thats just not an option.
>>>
>>> for file storage (including backup files from a database), raid5 is
>>> probably fine... for primary database tablespace storage, I'd only use
>>> raid1 or raid10.
>>
>> RAID-10 has only one perfect application, and that's with exactly four
>> disks. It can't use fewer, and the next larger step is 8, where other
>> flavors of RAID usually make more sense. But, for the 4-disk
>> configuration, it's unbeatable unless you need capacity more than
>> speed and redundancy. (In that case, you go with RAID-5.)
>>
>> RAID-10 gives the same redundancy as RAID-50: guaranteed tolerance of
>> a single disk lost, and will tolerate a second disk lost at the same
>> time if it's in the other half of the RAID. RAID-10 may also give
>> better performance than RAID-50. I'm not sure because you're trading
>> off more spindles against more parity calculation with the RAID-50.
>> At any rate, RAID-10 shouldn't be *slower*.
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>>
> It seems like you know / like RAID-10 a lot :)
>
> So, how does it perform with 6 discs for example? Say I have 3 HDD's in
> RAID-0, and another 3 in RAID-0, then RAID-1 the 2 RAID-0 stripes. How
> well would that work?
> And what would you recommend on 8 / 10 HDD's?
>
What you are describing would be raid 0+1 not raid 10. Most docs I have read
state that raid 10 is more fault tolerant. Here is one that explains it better;
http://www.pcguide.com/ref/hdd/perf/raid/levels/multXY-c.html
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