I wasn't sure if this qualifies as a newbie question or not, but I figured since it seems simple enough that I would post it here.
About a month ago I cobbled up a server from an old computer and HDD. Feeling ambitious, I decided to spend a little cash on a set of 3 1TB hdds when they went on sale. With some help from a friend (who I don't think is a member of these boards), I was able to get Debian up and running as well as Samba and was also able to access my share over the home network. (Amazingly this is from having almost little knowledge of the command line and *nix distros in general).
Yesterday I added a fourth hard drive that wasn't part of the raid array to the set, and while at first it didn't recognize the new hdd (it does now), it made note that one of the drives from my raid array had been completely removed, yet in POST all four drives show up.
Below is the detail for md0 in mdadm:
Version : 1.2
Creation Time : Wed Feb 2 00:55:33 2011
Raid Level : raid5
Array Size : 1953518592 (1863.02 GiB 2000.40 GB)
Used Dev Size : 976759296 (931.51 GiB 1000.20 GB)
Raid Devices : 3
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Wed Mar 2 01:39:32 2011
State : clean, degraded
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : sas:0 (local to host sas)
UUID : 67504025:838a3320:19da5a54:fad2ec4f
Events : 124
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 0 0 1 removed
2 8 65 2 active sync /dev/sde1
And here are a list of drives/partitions that show up when I "ls /dev/sd*"
/dev/sda /dev/sda2 /dev/sdb /dev/sdc /dev/sdd /dev/sde1
/dev/sda1 /dev/sda5 /dev/sdb1 /dev/sdc1 /dev/sde
Now I know that the syntax for adding a new drive into a raid array via mdadm is "mdadm --add /dev/md1 /dev/sdd1", but that renders itself useless if I can't have all four drives in the RAID5 array.
So I guess after all of this my question is: where did my second drive in the RAID array go and how do I get it back? (Before anyone figures it's a bad drive I did a SMART test on all drives yesterday and they are all fine).