Date: Sat, 18 Dec 2004 17:31:56 -0600 From: wbwither@bobball.uchicago.edu To: freebsd-questions@freebsd.org Subject: Identical hard drives, different disklabel sectors/cylinders Message-ID: <20041218233156.GA10895@bobball.uchicago.edu>
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Hi all, I've got a problem question about my hard drives. I've installed two brand-new Western Digital 250GB drives on the same channel of a Maxtor-branded PCI/IDE controller (Promise chipset). I've tried different channels, different cables, and using the motherboard's IDE controller -- same thing every time. Here's from /var/log/messages: Dec 18 15:59:23 /kernel: ad4: 238475MB <WDC WD2500SB-01KBA0> [484521/16/63] at ata2-master UDMA100 Dec 18 15:59:23 /kernel: ad5: 238475MB <WDC WD2500SB-01KBA0> [484521/16/63] at ata2-slave UDMA100 So you can see it's identifying them the same at startup. Now: su-2.05b# disklabel ad4 # /dev/ad4c: type: unknown disk: amnesiac label: flags: bytes/sector: 512 sectors/track: 63 tracks/cylinder: 255 sectors/cylinder: 16065 cylinders: 30400 sectors/unit: 488392002 rpm: 3600 interleave: 1 trackskew: 0 cylinderskew: 0 headswitch: 0 # milliseconds track-to-track seek: 0 # milliseconds drivedata: 0 8 partitions: # size offset fstype [fsize bsize bps/cpg] c: 488392002 0 unused 0 0 # (Cyl. 0 - 30400*) e: 488392002 0 vinum # (Cyl. 0 - 30400*) su-2.05b# disklabel ad5 # /dev/ad5c: type: unknown disk: amnesiac label: flags: bytes/sector: 512 sectors/track: 63 tracks/cylinder: 16 sectors/cylinder: 1008 cylinders: 484520 sectors/unit: 488397105 rpm: 3600 interleave: 1 trackskew: 0 cylinderskew: 0 headswitch: 0 # milliseconds track-to-track seek: 0 # milliseconds drivedata: 0 8 partitions: # size offset fstype [fsize bsize bps/cpg] c: 488397105 0 unused 0 0 # (Cyl. 0 - 484520*) e: 488397105 0 vinum # (Cyl. 0 - 484520*) So you can see, the "sectors/cylinder", "cylinders", and "sectors/unit" are all different, and this results in slightly different final sizes. I've set up vinum to create a mirror using the smaller of the two sizes, and it seems to be working fine, but I'm still worried about the implications of this. Could this mean that one of my hard drives is failing? (Again, they're both brand new.) I tried "disklabel -R"'ing each drive to look like the other one (booting in single-user mode), but it wouldn't let me. So I'm smack out of ideas. I'd appreciate any info or suggestions. Thanks, -Brock Witherspoon
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