Re: Mark IV data download broken

[Doug Welch <welch@physics.mcmaster.ca>]

Chris,

You are talking to the wrong guy here. I have vast RAID experience -
including a huge RAID 5 set which had a two-disk failure, rendering
the entire thing useless. Tape backups? Yes, they were configured too,
but a "minor" change to the network rendered them useless a month before
the two-disk failure. You can never have too much backup!

The short answer is that my drives are all mirrored once a day and
that critical things are RAID'ed. This dataset was not considered
"Criticality 1", since it could be retrieved on an hour's timescale
if needed from a disk mirror elsewhere in the builiding.

Cheers,
Doug

On Mon, 2005-01-31 at 12:23, Chris Albertson wrote:
> Have you looked into Linux software RAID?  I tested a software
> mirrored system a couple years ago by pulling the power cable
> off of a disk while the system was up and serving data.  Users
> did not even notice that a drive had failed.
> 
> This used to be an exotic feature but now with $100 drives the
> feature only costs $100.  Worth the effort if you have loads
> of data.
> 
> An extra bonus is that until one drive does fail
> your system is ctually faster because reads can be done in 
> parallel across the mirored drives.  The I/O rate for
> reads is almost doubled.  All for the price of one disk drive.