Messages in this thread | | | Date | Tue, 27 Nov 2001 00:38:43 -0700 | From | Andreas Dilger <> | Subject | Re: Journaling pointless with today's hard disks? |
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On Nov 26, 2001 16:16 -0800, Andre Hedrick wrote: > On Mon, 26 Nov 2001, Andreas Dilger wrote: > > What happens if you have a slightly bad power supply? Does it immediately > > go read only all the time? It would definitely need to be able to > > recover operations as soon as the power was "normal" again, even if this > > caused basically "sync" I/O to the disk. Maybe it would be able to > > report this to the user via SMART, I don't know. > > ATA/SCSI SMART is already DONE! > > To bad most people have not noticed.
Oh, I know SMART is implemented, although I haven't actually seen/used a tool which takes advantage of it (do you have such a thing?). It would be nice if there were messages appearing in my syslog (just like the AIX days) which said "there were 10 temporary read errors at block M on drive X yesterday" and "1 permanent write error at block M, block remapped on drive X yesterday", so I would know _before_ my drive craps out after all of the remapping table is full, or the temporary read errors become permanent. (I have a special interest in that because my laptop hard drive sounds like a jet engine at times... ;-).
What I was originally suggesting is that it have a field which can report to the user that "there were 800 sync/reset operations because of power drops that were later found not to be power failures". That is what I was suggesting SMART report in this case (actual power failures are not interesting). Note also, that this is purely hypothetical, based on only a vague understanding on what actually happens when the drive thinks it is losing power, and only ever having seen the hex output of /proc/ide/hda/smart_{values,thresholds}.
Being able to get a number back from the hard drive that it is performing poorly (i.e. synchronous I/O + lots of resets) because of a bad power supply is exactly what SMART was designed to do - predictive failure analysis.
Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/
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