Mapping Raid drives?

satory · May 21, 2016

Hi,

So I decided to build a home media/home CI server and I have 6 4TB hard drives, and 1 240GB SSD. I plan to keep the SSD for the OS etc, and use the 6 HDD for storage. For this reason I also brought a RAID Card which has 2 SAS ports, and then 2 SAS to SATA cables.

I never messed around with RAID before and its been 10 years since I last built a computer, so I'm a little behind the times... I do plan to install Ubuntu Server on my machine, so I'm wondering how can I identify each of the HDD, so that if one fails, I know which physical drive it is?

AdmnPower · May 21, 2016

Most of the time you can do this one of two ways, most RAID card manufacturers make a software utility that you can install that will monitor your drives and notify you if any of them have failed and which port the failed drive is plugged into so you can identify it. I'm not sure how good they are about making utilities that support linux though.

A second way is that you'll likely notice a performance degradation if you lose a hard drive at which point you could reboot your server and take a look at the array health in the RAID configuration utility and identify the problem drive from there.

Lurick · May 21, 2016

I thought Ubuntu server did it's mapping pretty much 1:1 meaning if you have 2 SATA ports and then a bunch of SAS to drives the two SATA drives would be SDA and SDB followed by the SAS drives which would be SDC with the SDC drive mapping to the first SAS port and cable 1, and so on like that.

Jarsky · May 21, 2016

Typically the RAID cards have alarms, so it will make an annoying sound when a drive falls over.

You can query the RAID card to see which drive has died. It will show you the drive and which port its connected too.

So theres 2 ways to physically identify which drive it is:

- When you setup the RAID, mark which port each drive is on.For example you might use sticky dots and stick one to the end of each drive, with P0, P1, P2, P3, etc...

- The other way, is that if you query the drive on the RAID card, you can see the serial number. You can match this with the drive. If they're WD's you will see a sticker at the end of the drive with about 4-5 characters - that is the last 4-5 characters of the serial number.

Additionally - If you have a more advanced enclosure with hotswap and activity lights, your cages may support signaling So the light on the cage for the failed drive will flash/change color.