Understanding default ZFS RAID10 setup

[lildergs]

Hi all,
I just installed Proxmox 5 on a 4 disk ZFS RAID 10.
This is the disk config am running after the install:

I am a little confused by how the installer laid out the ZFS structure and partitions.

Here are my drives:

root@ProxBox:~# lsblk

NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT

sda      8:0    0   3.7T  0 disk

├─sda1   8:1    0  1007K  0 part

├─sda2   8:2    0   3.7T  0 part

└─sda9   8:9    0     8M  0 part

sdb      8:16   0   3.7T  0 disk

├─sdb1   8:17   0  1007K  0 part

├─sdb2   8:18   0   3.7T  0 part

└─sdb9   8:25   0     8M  0 part

sdc      8:32   0   3.7T  0 disk

├─sdc1   8:33   0   3.7T  0 part

└─sdc9   8:41   0     8M  0 part

sdd      8:48   0   3.7T  0 disk

├─sdd1   8:49   0   3.7T  0 part

└─sdd9   8:57   0     8M  0 part

sr0     11:0    1   274M  0 rom 

zd0    230:0    0     8G  0 disk [SWAP]

Here is my ZFS config:

root@ProxBox:~# zpool status

  pool: rpool

 state: ONLINE

  scan: none requested

config:


 NAME        STATE     READ WRITE CKSUM

 rpool       ONLINE       0     0     0

  mirror-0  ONLINE       0     0     0

    sda2    ONLINE       0     0     0

    sdb2    ONLINE       0     0     0

  mirror-1  ONLINE       0     0     0

    sdc     ONLINE       0     0     0

    sdd     ONLINE       0     0     0


errors: No known data errors

I expected something more like this:
Each drive has a boot partition s*1
sda2 & sdb2 is one data mirror
sdc2 &sdd2 is another data mirror

Here are my questions:

What are sda1 and sdb1?

Why does mirror-0 mirror specific partitions (sda2 and sdb2) and mirror-1 mirrors whole drives (sdc and sdd)?

What is sr0?

Where is the zd0 swap space on the drives?

 

[guletz]

Hi,

I guess, that your 4 HDD are not have the same size. So the zfs, has made one additional partion on the first 2 of them(sda1 and sdb1). The last partion (8 MiB is a default for zfs) is exactly for the same reason, could be very small difference in capacity for 2 HDD label by the manufacturer with the same capacity.

sr0 is your CD_ROM/DVD

zd0 is a slice of your rpool pool . You can see what you have with this(run as root ):

zfs list

 

[lildergs]

Thanks for the response -- that makes sense.
I went and checked the bytes per disk however, and they look the same:

root@ProxBox:~# lsblk -b

NAME     MAJ:MIN RM          SIZE RO TYPE MOUNTPOINT

sda        8:0    0 4000787030016  0 disk

├─sda1     8:1    0       1031168  0 part

├─sda2     8:2    0 4000777575424  0 part

└─sda9     8:9    0       8389120  0 part

sdb        8:16   0 4000787030016  0 disk

├─sdb1     8:17   0       1031168  0 part

├─sdb2     8:18   0 4000777575424  0 part

└─sdb9     8:25   0       8389120  0 part

sdc        8:32   0 4000787030016  0 disk

├─sdc1     8:33   0 4000776716288  0 part

└─sdc9     8:41   0       8388608  0 part

sdd        8:48   0 4000787030016  0 disk

├─sdd1     8:49   0 4000776716288  0 part

└─sdd9     8:57   0       8388608  0 part

And the bytes don't line up!

sda2: 4000777575424
sdb2: 4000777575424
sdc: 4000787030016
sdd: 4000787030016

So once again I am confused.

Help! Thanks!

 

[LnxBil]

Please use CODE tags to display command output. Much easier to read and understand.

The partitions sda1 and sda2 are both used by the bootloader. Please check yourself with a partition program. The type is normally BIOS Boot.

 

[lildergs]

Got it & thanks for the CODE hint.

I did check with a partition tool earlier and was confused why they were not on all disks.

I suppose this is because if both sda or sdb were bad the pool would be broken regardless so there is no point having those partitions on more than sda and sdb.

Am I understanding things right?

 

[LnxBil]

Yes, you have only "one" backup boot block on the second disk. So be aware if you run a zraid-2 or higher and the first two disks fail :-D