Pallai Roland wrote: > Molle Bestefich wrote: > > Claas Hilbrecht wrote: > > > Pallai Roland schrieb: > > > > this is a feature patch that implements 'proactive raid5 disk > > > > replacement' (http://www.arctic.org/~dean/raid-wishlist.html), > > > > > > After my experience with a broken raid5 (read the list) I think the > > > "partially failed disks" feature you describe is really useful. I agree > > > with you that this kind of error is rather common. > > > > Horrible idea. > > Once you have a bad block on one disk, you have definitively lost your > > data redundancy. > > That's bad. > > Hm, I think you don't understand the point, yes, that should be > replaced as soon as you can, but the good sectors of that drive can be > useful if some bad sectors are discovered on an another drive during the > rebuilding. we must keep that drive in sync to keep that sectors useful, > this is why the badblock tolerance is. Ok, I misunderstood you. Sorry, and thanks for the explanation. > It is the common error if you've lot of disks and can't do daily media > checks because of the IO load. Agreed. > > What should be done about bad blocks instead of your suggestion is to > > try and write the data back to the bad block before kicking the disk. > > If this succeeds, and the data can then be read from the failed block, > > the disk has automatically reassigned the sector to the spare sector > > area. You have redundancy again and the bad sector is "fixed". > > > > If you're having a lot of problems with disks getting kicked because > > of bad blocks, then you need to diagnose some more to find out what > > the actual problem is. > > > > My best guess would be that either you're using an old version of MD > > that won't try to write to bad blocks, or the spare area on your disk > > is full, in which case it should be replaced. You can check the > > status of spare areas on disks with 'smartctl' or similar. > > Which version of md tries to rewrite bad blocks in raid5? Haven't followed the discussions closely, but I sure hope that the newest version does. (After all, spare areas are a somewhat old feature in harddrives..) > I've problem with "hidden" bad blocks (never mind if that's repairable > or not), the rewrite can't help, cause you don't know if that's there > until you don't try to rebuild the array from degraded state to a > replaced disk. I want to avoid from the rebuiling from degraded state, > this is why the 'proactive replacement' feature is. Got it now. Super. Sounds good ;-). (I hope that you're simply rebuilding to a spare before kicking the drive, not doing something funky like remapping sectors or some such..) - 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
