On Thu, 20 Oct 2005, Dale Blount wrote: > On Wed, 2005-10-19 at 22:09 -0700, Randy.Dunlap wrote: > > On Mon, 17 Oct 2005 15:24:04 -0400 Dale Blount wrote: > > > > > Hello, > > > > > > I just added 2 external 1TB+ scsi devices to my i686 linux server > > > running 2.6.13.4 connected to external LSI MPT card. fdisk and df both > > > show the sizes correctly (see below), but I'm worried that dmesg reports > > > them incorrectly. > > > > > > SCSI device sda: 2460934144 512-byte hdwr sectors (160487 MB) > > > SCSI device sdb: 3790438400 512-byte hdwr sectors (841193 MB) > > > > > > I don't think it's as simple as a variable overflow because both > > > sdkp->capacity and mb look to be cast as unsigned long longs. I know a > > > workaround is to present less data per LUN, but I'd like to use it as > > > it's setup currently if possible. Is this just printing incorrectly or > > > will I run into trouble when the device gets more full? > > > > The casts to (unsigned long long) just fix the printk() args to match > > the format strings (and eliminate warnings). > > > > Looks to me like sdkp->capacity is correct. The <mb> value looks > > way off. Since it's just printed here for user info, I don't see > > how it can be a problem later on. > > > > That's what I was hoping, but I didn't know for sure. I figured I'd > better ask to make sure my data wouldn't get truncated when the disk got > fuller. Between my first post and now, I've tested it by filling the > drive with data and testing the md5sums for each file and it seems to > work. Other than the odd MB size reported, it seems to work just fine. > > > I don't see the error just yet. Are there any other SCSI device- > > related messages near these? And just to confirm, but you must > > have CONFIG_LBD (Large Block Device) enabled, right? > > > > No, there are no other related messages near these other than the > standard vendor/versions. I did not enable CONFIG_LBD since the help > says "bigger than 2TB", and I partitioned the storage system to present > disks smaller than that. I guessed at CONFIG_LBD=y last night. Today I did the arithmetic with CONFIG_LBD=n... and found the overflow. In drivers/scsi/sd.c, approx. line #1260: sector_t sz = sdkp->capacity * (hard_sector/256); sz is 32 bits. capacity is 32 bits with a value of 2,460,934,144 == 0x92ae_e000. Then we multiply that by 2 (512 / 256)... and it overflows. Should be hex 1_255d_c000, but we drop the '1'. The rest of the calculation (with this new value) does result in the 160487 MB, matching your log message. I think that you can fix it (patch it) by changing that line to make 'sz' be type 'u64' for now. u64 sz = sdkp->capacity * (hard_sector/256); But those divides by 1250 and 1950 are still voodoo to me. -- ~Randy - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
