Unsupported sector size 520

While setting up a new DIY server using 15k RPM SAS drives, I ran across some drives which came from the factory with 520 byte sectors (oops).  You'll be able to hook them up and see that they show up as /dev/sdX, but you won't be able to do anything with them (such as read/write or partition).

If you look in /var/log/messages, you will see useful information:

Mar  9 08:08:54 vhc-carthage kernel: sd 6:0:7:0: [sdh] Attached SCSI disk
Mar  9 08:08:57 vhc-carthage kernel: ...ready
Mar  9 08:08:57 vhc-carthage kernel: sd 6:0:8:0: [sdi] Unsupported sector size 520.
Mar  9 08:08:57 vhc-carthage kernel: sd 6:0:8:0: [sdi] 0 512-byte logical blocks: (0 B/0 B)
Mar  9 08:08:57 vhc-carthage kernel: sd 6:0:8:0: [sdi] 520-byte physical blocks
Mar  9 08:08:57 vhc-carthage kernel: sd 6:0:8:0: [sdi] Write Protect is off
Mar  9 08:08:57 vhc-carthage kernel: sd 6:0:8:0: [sdi] Write cache: disabled, read cache: enabled, supports DPO and FUA
Mar  9 08:08:57 vhc-carthage kernel: sd 6:0:8:0: [sdi] Unsupported sector size 520.
Mar  9 08:08:57 vhc-carthage kernel: sd 6:0:8:0: [sdi] Attached SCSI disk

The fix for this is pretty simple in RHEL6/CentOS6.  Major pointers for this came from PissedOffAdmins.

# yum install sg3_utils

# sg_scan -i
/dev/sg8: scsi6 channel=0 id=7 lun=0
    NETAPP    X287_S15K5288A15  NA00 [rmb=0 cmdq=1 pqual=0 pdev=0x0]
/dev/sg9: scsi6 channel=0 id=8 lun=0
    NETAPP    X287_S15K5288A15  NA00 [rmb=0 cmdq=1 pqual=0 pdev=0x0]

Now you should format the offending drive using the "sg_format" command.

[root@vhc-carthage /]# sg_format --format --size=512 /dev/sg8

    NETAPP    X287_S15K5288A15  NA00   peripheral_type: disk [0x0]
Mode Sense (block descriptor) data, prior to changes:
  Number of blocks=573653847 [0x22314357]
  Block size=520 [0x208]

A FORMAT will commence in 10 seconds
    ALL data on /dev/sg8 will be DESTROYED
        Press control-C to abort

After this, the disk should work when connected to a regular SAS controller (in my case, a 16-port LSI).

Final note: You will probably find that the disks which have been converted from 520 byte sectors to 512 byte sectors will not perform as well as a disk that was originally manufactured for use as a 512 byte sector drive.  At least, that has been my experience with a sample size of just two drives (and I don't plan on purchasing the wrong drives again).