question on vinum

[Chuck Swiger]

Mikhail P. wrote:
> On Wednesday 27 October 2004 05:33, secmgr wrote:
[ ... ]
>> If you want to do that, then you want raid5.  If either a concat or
>> stripe set looses a drive, the data will need to be restored.
> 
> Are there known methods/techniques to restore data from failed concat or 
> stripe volumes?

Certainly.  It's known as "taking a backup", perhaps to a tape drive or some 
other form of storage.  If you don't have a backup, and you lose a disk in a 
RAID-0 config, you will effectively lose all of the data.

[ ... ]
> Does striping require an additional drive too?

No.

> Or it is very similar to 
> concat, except for it stores data across all the spindles?

Yes, that's right.

> Does it also mean that it is harder to recover stripped volume?

The question isn't well-phrased: you can't recover data from either if you 
lose a drive.

> As for raid5 - it requires an additional drive. Are there any requirements for 
> the drive? E.g. would it work as having 3 x 200GB for stripe + additional 
> 20GB drive that will be used for control blocks?

No.  All of the drives need to be the same size.  With RAID-5, which drive is 
used to hold parity data rotates on a stripe-by-stripe basis to balance out 
the load.

> And what happens here if 
> 20GB drive fails - will I be able to rebuild it and continue using raid?

You can rebuild a RAID-5 volume if a single drive fails without losing data.

-- 
-Chuck