On 31/01/2022 19:21, Phil Turmel wrote: > On 1/31/22 14:07, Geoff Back wrote: > >> If a disk has one or more bad sectors, surely the only logical action is >> to schedule it for replacement as soon as a new one can be obtained; and >> if it's still in warranty, send it back. If the data is valuable enough >> to warrant use of RAID (along with, presumably, appropriate backups) >> surely it is too valuable to risk continuing to use a known faulty disk? >> >> In which case, I would suggest that dangerous experiments that try to >> force the disk to reallocate the block are arguably pointless. >> >> Just my opinion, but one that has served me well so far. >> >> Regards, >> >> Geoff. > I would be surprised if you got warranty replacement just for a few > re-allocated sectors. The sheer quantity of sectors in modern drives > and the tiny magnetic domains involved means **no** drive is error-free. > Just most defects are identified and mapped out before shipping. > Reallocations cover the marginal cases. > > I replace drives when re-allocations hit double digits, though I've had > to run a few corners cases well past that point. > > Phil I've never had a problem with any manufacturer replacing a drive that reallocates even one sector within 12 months. I just send them a "smartctl -x" log. I can't remember the last time I had a drive do its first sector reallocate after 12 months but before end of warranty, so I can't really comment on what the manufacturers might be like in that case. Yes, there will be original manufacturing defects that are mapped out before shipping. That's fine and doesn't bother me. But any drive that has developed a bad sector after installation will in my experience tend to develop more in time, and on a few occasions I've seen drives that reallocate in "bursts" so the count remains fairly stable for a while then jumps up 40 or 50 sectors within a few minutes. I generally reckon that as soon as one bad sector appears on an out-of-warranty drive (which is alerted by SMART monitoring) it's time to start looking at replacement as soon as reasonably possible, subject to drive availability and a good time for the swapout and rebuild. That might mean next-day a drive and replace immediately or it might mean within a couple of weeks, depending on drive availability and the operational cost of a total array failure. I did come across a customer array on one occasion with between 50 and 1200 reallocated sectors on each of the 12 drives in the array. it was working and generally performance was as expected, but I would not have dared to replace/rebuild any of those disks (it was ultimately done as a complete new array and data migration). As always, this is my (experience-based) opinion and your mileage may vary. Regards, Geoff. -- Geoff Back What if we're all just characters in someone's nightmares?
