Hey all,

 

For background I have a system with 3 drive bays, 2 are full one is empty. I currently have one cage with 4 drives, one cage with five drives. All the drives are 3TB. I'm planning on putting in 5 new 4TB drives this weekend which means I need to upgrade my parity drive from a 3TB to a four. The problem is I don't know which drive is the parity drive. 4 four cage has 4 drives in it all with blue lights. My 5 cage has 5 drives in it four with green lights, one with an orange light.

 

Is there a simple way to tell which drive is the parity drive? Can I make the light blink, is there some command for that? Or do I simply shut it down, pull a drive, check the list and rinse and repeat until I find the parity drive?

 

Thanks in advance.

Are those lights showing drive activity?

If yes, then you can chose 2 different data drives e.g. disk1 and disk2.

Then you copy a file to disk1 and note what lights are showing activity.

Then you copy a file to disk2 and note what lights are showing activity.

The light which is on both times indicates your parity.

 

If the lights show only spinning drives you have to wait for them to spin down or

spin them down manually and do the above testing.

 

Read the serial number from the drive.

You can force drive activity by with this command

  cat /dev/sd#1 > /dev/null

Where # is the letter for your parity drive. That will pin the activity light on (ctrl+c to stop it) so you can tell which bay contains your disk.

You could look in your web console. The web console shows both data drives and parity drives.  The parity drive will be the first drive, and will be identified by a number that looks like this:

 

ST3000DM001-1CH166_W1F12655 (sdb) 2930266532

 

The serial number is the last 8 numbers in this identification string.  In this case it tells you /dev/sdb  Also the serial number may be different depending on manufacturer.

 

the /dev/sdX drives are usually assigned in order from port0 to port 2 (for a basic 3 drive system).  If your parity is on /dev/sdc, and your flash is on /dev/sda, start with sdb and port0 and count up until you get to sdc. in this example, your drive is most likely on port1.  Pull port 1 and verify the serial number.  If the serial number matches, you have the parity drive.  Its what I did to identify my parity drives when I upgraded from 2tb to 3tb.

 

Can I make the light blink, is there some command for that?

 

As noted above, there are a couple ways to cause the activity light to blink.  If the lights on your cages don't blink with activity, but just light up when the drive is rotating (I've seen some cages with this behavior);  then spindown all drives; then do a write to disk1.  This will cause disk1 and the parity drive to spin up.  Then do another spindown; and this time write to disk2.  This will cause disk2 and the parity drive to spin up.    You can then identify the parity drive.

 

 

Or do I simply shut it down, pull a drive, check the list and rinse and repeat until I find the parity drive?

 

This is, of course, a straightforward way to do it with the system shut down.    Simply note the serial # of the drive on the Web GUI (as you clearly know);  then simply look at the drives until you find it.

 

By the way, a small Dymo label on each drive is a good idea that will preclude this problem in the future.  Either lable them "P", "1", "2", ... -- OR use the last 4 digits of the serial # for the labels (which eliminates any dependencies on which slot they're in, in case you ever change the config.

 

 

Note, however, that if you plan to use the old parity drive as a data drive, you do not NEED to identify which physical drive it is      Just install the 4TB drive you want to use as the new parity drive;  then Stop the array and assign it as the parity drive [Note the serial # of the old parity drive].    Then -- after parity has been rebuilt on the new parity drive -- you can assign the old parity drive as a new data drive.