On Sunday 09 January 2005 00:09, Guy wrote: > Maarten said: > "Normally, the minute a drive fails, it gets kicked and the spare would > kick in and md syncs this spare. We now have a non-degraded array again." > > Guy says: > But, you make it seem instantaneously! The array will be degraded until > the re-sync is done. In my case, that takes about 60 minutes, so 1 extra > minute is insignificant. No, sure it is not instantaneous, far from it. Sorry if I made that impression. On my system it takes a whole lot longer than 60 minutes, more like 360 minutes. (in my other array where I use whole-disk 160 GB volumes). > Marrten said: > "Yes, but this would be impossible to do, since md cannot anticipate > _which_ > disk you're going to fail before it happens. ;)" > > Guy says: > But, I could tell md which disk I want to spare. After all, I know which > disk I am going to fail. Maybe even an option to mark a disk as "to be > failed", which would cause it to be spared before it goes off-line. Then > md could fail the disk after it has been spared. Neil, add this to the > wish list! :) Yes, that would be a smart option indeed :) It gets rid of the window where any failure would be fatal. But I suppose Neil is overworked as it is. > EMC does this on their big iron. If the system determines a disk is having > too many issues (bad blocks or whatever), the system predicts a failure, > the system copies the disk to a spare. That way a second failure during > the re-sync would not be fatal. And a direct disk to disk copy is much > faster (or easier) than a re-build from parity. This is how it was > explained to me about 5 years ago. No idea if it was marketing lies or > truth. But I liked the fact that my data stayed redundant while the spare > was being re-built. This would not work if a drive failed, only if a drive > failure was predicted. Another cool feature... the disk array then makes a > support call. The disk is replaced quickly, normally before any redundancy > was lost. Hehe. Cool. Big iron -> You indeed get what ya pay for :-)) - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
