logical volumes & striping

[David Higgen]

In article <9105101949.AA20619 at centrs1.CENTRCN.UMontreal.CA>, chouinar at centrcn.umontreal.ca (Luc Chouinard) writes:
> We have 6 scsi disks on two controlers, and we are
> considering using a striped logical volume for one
> of our partitions.
> 
> We currently believe that striping is always a good thing
> to do.  
> 
> We have just been advised by a knowledgeable person that
> this would not be true in all cases, specifically ours.
> And the explanation that was given to us makes sense.

Would you care to mail me this explanation? I would like to see
if it makes sense to me & may be able to advise you better: I am the
author of SGI's logical volume implementation.

> More specifically, we would like to know if there is an
> overhead associated with accessing a single block in a
> striped logical volume, versus a standard partition.

The overhead is negligible: a sufficiently small fraction of
a percent that we have not been able to detect it in practical
performance measurements.


		Dave Higgen (daveh at xtenk.asd.sgi.com)