RAID 10 - 2 Disk Failure, how to know which drives are mirrored and if data is safe?

Question

The server is currently experiencing a 2 disk failure and was looking for a way to know if my data is lost or not. I tried searching everyone but I didn't find an answer (I'm sorry - new to this).

I ran (cat /proc/mdstat):

Personalities : [raid10] [raid1] md0 : active raid1 sdb1[2] sda1[0]
      1023936 blocks super 1.0 [2/2] [UU]

md1 : active raid10 sdb2[2] sda2[0]
      24558592 blocks super 1.1 512K chunks 2 near-copies [4/2] [U_U_]

md2 : active raid10 sdb3[2] sda3[0]
      1926568960 blocks super 1.1 512K chunks 2 near-copies [4/2] [U_U_]
      bitmap: 15/15 pages [60KB], 65536KB chunk

unused devices: <none>

As I know, an underscore means that the disk failed. This RAID 10 is running 4 X 1 TB disks (sg1, sg2, sg3, sg4). How do I know which is stripped/mirrored with same data and if my data is not lost?

Thanks for the help in advance.

Answer 1

You have two failed drives. (sdc and sdd). In a "near-copies" layout data are being replicated to disk near them. Near means the number inside bruckets [].

Ιn your case what the likely scenarios before failure is this:

sdb[2] sda[0] sdc[1] sdd[3]

that means data on sda replicated on sdc and data on sdb replicated on sdd

loosing sdc and sdd will not result in a data loss.