Slashdot Mirror
Data Recovery from ReiserFS RAID Array?
Ruatha asks: "We've recently had a problem with a ReiserFS RAID-5 array - two of the disks failed and, of course, some of the people using the array didn't have backups of their data...Ontrack have returned the disks because they can do nothing with them due to the FS we used on the array. Does anyone know of a company that can deal with data recovery from a ReiserFS RAID-5 array?"
Simultaneous disk failure is about as rare as winning the lotto while simultaneously having you and your friend on the other side of the planet get struck by lightning - unless there's a common larger problem (e.g. power surge to both drives or something).
As a practical example, 4 or 5 years ago I had large amount of disks attached to some large oracle servers, roughly on the order of 600 or so hard drives in several arrays taking up several racks, all the same manufacturer/model, with a handful of groupings of revision/lot/date.
This set of disks was seeing fairly constant and heavy activity for a few years while I was there. As you can imagine, with 600 disks and the usual MTBF numbers, we quite regularly had disk failure. We kept a few spares onsite and replaced them as they failed, then exchanged the dead drive for a new spare. As I roughly remember it, we probably averaged about one disk failure every 2-3 weeks. Two, perhaps three times, we had a double disk failure during a 24 hour period - but they were never close enough that we didn't have plenty of time to replace the first (and in any case, odds are slim that two failed out of 600 would happen to affect the same data).
Of course, another point back at the original guy with the failed disks - don't use raid 5, chunk out some more money (disks are cheap) and do proper mirroring - and if you stripe use 1+0, not 0+1.
11*43+456^2
This is certainly true, but you should consider the flipside of it. The typical way it works with IT departments is that they are given unfunded mandates right and left. There is no possible way they can do everything with the money they have. What should happen is that some stuff should be taken off their plate. But they rarely have the political pull needed to do that, so what actually happens is that either everything is done poorly or the IT guys work on what they think is important.
So before you go pointing fingers at the IT department's attitude, it would be good to ask, "Did they tell the managment that they needed a way to back up those machines? And did the managers give them the necessary time and funds?"
Every IT person I know with a bad attitude has didn't start that way; they acquired it through years of crappy management.