[CentOS] Re: RAID5 or RAID50 for database?

Thu May 22 17:16:31 UTC 2008
Scott Silva <ssilva at sgvwater.com>

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;

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