On Fri, 2013-07-26 at 19:01 +0100, Dom wrote: > On 26/07/13 17:53, Ralf Mardorf wrote: > > On Fri, 2013-07-26 at 11:54 -0400, Stefan Monnier wrote: > >>> The system in question is running from an SSD, which I assume changes your > >>> assumptions quite a bit. With a traditional HDDs, the loss of power > >>> causes a head crash, etc which does in turn lessen the life of the drive. > >> > >> Actually, I fail to see why a power outage would have any negative > >> effect on an HDD (e.g. why would the "head crash"?). > > > > In the old days the heads were not driven back, but for around more than > > 20 years the heads will park by the momentum of the turns, when there > > should be a blackout. IIRC if the drives didn't turn fast enough, the > > heads could crash. Today a power outage definitively doesn't cause a > > crash and AFAIR even my old 42 MB SCSI survived power outages. > > True. Back in those days the heads on some disks had to be sent a "park" > command before powering off and what that did was to move the head to an > reserved area of the disk before landing. Modern drives park the heads > off the disks completely. > > I do remember so old 500MB mainframe disk units (14 inch 10 platter or > so, 4 per unit) that had a slight fault. The normal procedure was to > press the "offline" button, which retracted the heads from the disk, > then press the "power" button to turn them off. Due to a glitch in the > circuitry this would sometimes result in a surge in the head actuator > coil and the heads would move back across the disks just as they stopped > spinning, resulting in major damage to the entire unit. Later a small > button was fitted which disconnected the coil and we had to hold that > down until the disk had stopped spinning.
JFTR in the meantime I read the German Wiki and it claims that heads automatically are parked since 1989, IOW >= 24 years ago there was this issue. http://de.wikipedia.org/wiki/Head-Crash -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/1374865587.680.4.camel@archlinux
