At times I really hate Slashdot (actually nearly all the time these days), I remember when Slashdot was a cool website but now….it's not so cool now! I suppose its like saying 'I only liked the early stuff before anyone had heard of them…'.
Now they've picked up on a very old article about RAID-5 being broken etc and I've had to field emails from various well-meaning people pointing me in the direction of said article! Now the article is written by our very own fellow blogger Robin Harris aka StorageMojo and as such should be read carefully. But most people don't bother to read articles carefully and just jump up and down excitedly. It's a good article BTW and does lead you to think (well, I hope it does).
Yes, RAID-5 is kind of broken but we don't use RAID-5 for any disk over the size of 300Gb; okay, we RAID-5 some 500 Gig drives but only after explaining to the user that we have a gun aimed at their foot but if they insist, we will do it but only if they are prepared to loose all their data and wait for a tape restore. We use RAID-6 or RAID-DP; this should be sufficient for drives upto 1.5Tb and we are considering what we do next to protect our disks. It is one of my favourite questions to vendors
'Parity RAID is broken, please discuss…'
It's always a good ice-breaker…
I saw that on slashdot as well, and didn’t even check to see how old the ZDNet article was.
It is good knowledge to have, and surely something that people weren’t necessarily thinking of when disk capacities were orders of magnitude lower….
“RAID5 Dead?”
Depends. For a lot of folks, certainly not the best option -bad blocks on rebuild and all that-.
At a former employer, certainly not a good choice as RTO would be very painful with RAID5 blow-out -but doable- with SRDF-A to remote site.
However, at a big client site I’m familiar with, RAID5 is the preferred option. Why? SVC synch mirrors to RAID5s at local/remote site. Certainly don’t want to spend extra on higher available RAID levels at either end, wouldn’t make sense. Why not RAID0? Let’s be reasonable, wouldn’t want the hassle of cleaning up after that either.
Maybe in the future as others get SVC like functionality at a controller level or switch -Invista- and LUNs are actually cross-site mirrored behind the scenes.. RAID5 is the preferred option at the array level -for those that can architect as described-.
Why do parenthesis turn into pound signs: # annoying