It can be very useful to know the serial number of a HDD. Say you have a FreeBSD server with 10+ hard drives, all the same make/model/size and one of the hard drives fails, how to you know which disk you need to unplug to replace it? On the sticker on HDD is the unique serial number of the HDD, so by matching this to the serial number reported from the failed disk dev you know which one to pull.
Here’s an example, the serial number on the physical HDD will look something like this:
On the command line, to see the serial number of an attached HDD you can use the
camcontrol identify command, if you are using AHCI,
ATA_CAM kernel option. This can usually be enabled by putting
/boot/loader.conf and reboot.
# camcontrol identify ada0 pass1: ATA-7 SATA 1.x device pass1: 150.000MB/s transfers (SATA 1.x, UDMA6, PIO 8192bytes) protocol ATA/ATAPI-7 SATA 1.x device model ST3200820AS firmware revision 3.AAD serial number 5QE0RCHD cylinders 16383 heads 16 sectors/track 63 sector size logical 512, physical 512, offset 0 LBA supported 268435455 sectors LBA48 supported 390721968 sectors PIO supported PIO4 DMA supported WDMA2 UDMA6 Feature Support Enabled Value Vendor read ahead yes yes write cache yes yes flush cache yes yes overlap no Tagged Command Queuing (TCQ) no no Native Command Queuing (NCQ) yes 32 tags SMART yes yes microcode download yes yes security yes no power management yes yes advanced power management no no automatic acoustic management no no media status notification no no power-up in Standby no no write-read-verify yes no 0/0x0 unload no no free-fall no no data set management (TRIM) no
Look for the
serial number field, as you can see the output from camcontrol on ada0 matches the picture above. Run this command against your failed HDD, assuming it isn’t really really broken in which case you will need to run it against all the other disks and go by process of elimination. If none of your disks have failed yet, it might be a good idea to record which serial number goes with which disk device, so when it does fail you know which S/N to look for.