Types of raid

J

jtvd78

Limp Gawd
Joined
Jul 27, 2009
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what types of raid is out there, what are they used for, redundancy??? performance??? both???
 
jtvd78 said:
but what about nested raid???(1+0, 5+0,0+5,etc.)
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What about it? The rationale is to provide an additional layer of RAID redundancy or speed on top of another RAID level, so RAID 10 would be a mirror of stripes, a RAID 50 would be a RAID 5 which is then striped.

The usual thing to note about nested RAID levels is that it doubles the amounts of disks necessary to provide the same amount of space.
 
is there nested raid like 100, 51,15,0+5,etc...

Do any products support this??
 
jtvd78 said:
is there nested raid like 100, 51,15,0+5,etc...

Do any products support this??
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Yes, but things get pretty silly, especially considering that for data protection RAID is no substitute for backup. RAID can not prevent data loss in MOST situations, it only protects against hard drive failure, if ANYTHING else goes wrong with your data, RAID is useless.

If you need more IOPS you are usually better off going to other solutions than you are nesting RAID levels beyond 10 or 50 etc.
 
jtvd78 said:
is there nested raid like 100, 51,15,0+5,etc...

Do any products support this??
Click to expand...
Almost all commercial RAID controllers support these features. Also, I do not recommend anyone use a cheap $200 and under or onboard RAID controller for anything other than RAID 1 or RAID 0. The ability to rebuild and performance of RAID 5 and 6 makes it a waste of good hard drives.
 
the types of raid that i mentioned, i could not find when looking at raid controllers
 
If you're spazzing out on how to use RAID (I did), take a pill (I do) and work out what you can do with what hardware you've already got then try it. Unless you actually prove that YOU can recover data when a data-protective raid array fails, it won't help your sanity. You need to actually build a quick mirroring array (RAID1) and break it, replace a disk and see if it works. Only then will you know.

Or do what I did - have a massive striping array for high speed and just keep decent enough backup discipline (And prey for the day when I know how a NAS really works)...

And that's it...
 
Can any raid 0 give you slower performance than single disks? If I get three harddrives, is there a reason NOT to put 2 in raid and leave 1 for backup?
 
If you have 3 HDDs to use, the only reason I can think of to deter one from throwing a RAID0 array together (For a new install on the O/S drive) is:

- None of them are identical enough so it won't work (Or would at least degrade the speed of the fastest drive)
- I don't have a backup disk (Which you do if you have 3 disks)
- RAID0 is twice as prone to HDD failure than notRAID0 (Which doesn't bother me since I have adequate BKP)

OK, reasonS

And since I decided on my RAID setup recently, I can say that:
a - You always need good backup anyway. Always
b - until you have a fileserver, there seems to be no need for data-protective RAID (ie 1, 0+1, 5 etc...)
c - Might aswell go for performance
 
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Raci said:
If you have 3 HDDs to use, the only reason I can think of to deter one from throwing a RAID0 array together (For a new install on the O/S drive) is:

- None of them are identical enough so it won't work (Or would at least degrade the speed of the fastest drive)
- I don't have a backup disk (Which you do if you have 3 disks)
- RAID0 is twice as prone to HDD failure that notRAID0 (Which doesn't bother me since I have adequate BKP)

OK, reasonS
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Who ever said the disk arent Identical? and it would default to the slowest drive ;)
 
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