Date: Sat, 5 May 2001 07:55:49 -0400 From: Bill Pechter <pechter@ureach.com> To: "Ron Klinkien" <rklinkien@chello.nl>, freebsd-scsi@FreeBSD.ORG Subject: Re: Recovered data with positive head offset field replaceable unit msg Message-ID: <200105051155.HAA22713@stage21.ureach.com>
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> Hi SCSI wizards, > > On one of my FreeBSD machines I found > this rather strange scsi message: > > > (da1:sym0:0:8:0): READ(06). CDB: 8 8 1 90 10 0 > > (da1:sym0:0:8:0): RECOVERED ERROR info:80198 asc:17,2 > (da1:sym0:0:8:0): Recovered data with positive head offset field replaceable unit: df sks:80,12 > > Thanks in advance. > > Regards, > Ron. Haven't seen something like that in years. In the old days of SMD disks and DEC RP06's and RM05's (mid 80's), I'd have said it was a servo tracking issue with the heads missing the data by a bit (possible bad spot on disk) which was recovered by the disk controller offsetting the heads a bit towards the center of the drive just a bit. The data was recoverable... by the drive moving the head just a little. Things like this were caused by bad spot on disk (servo platter or data platter) misalignment, dirt on the drive rails that caused the heads to bounce a bit while seeking or trying to stay on track, power fluctuations. Some idiot banging into the disks during a read operation. Folks -- do things like this still happen with modern scsi drives. Misalignment is probably out. Embedded servo's tend to eliminate a weak servo head. Dirt on drive rails -- nah. If it's a one shot error I wouldn't worry much -- but if it reoccurs... it's a problem. I've got a problem on one of the drives here that I know is the drive.da1: <SEAGATE SX910800N 8514> Fixed Direct Access SCSI-2 device da1: 10.000MB/s transfers (10.000MHz, offset 15), Tagged Queueing Enabled da1: 8669MB (17755614 512 byte sectors: 255H 63S/T 1105C) I get errors like this repeatedly on some parts of the disk: I plan to reformat it... I've considered turning off tagged queueing... sym0:1:control msgout: 80 20 79 d. sym0:1:control msgout: 80 20 6b d. (da1:sym0:0:1:0): WRITE(10). CDB: 2a 0 0 e2 4b 15 0 0 10 0 (da1:sym0:0:1:0): ABORTED COMMAND info:cf4b25 asc:4e,0 (da1:sym0:0:1:0): Overlapped commands attempted field replaceable unit: 1 sym0:1:control msgout: 80 20 1b d. sym0:1: message d sent on bad reselection. --Bill To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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