Adding two new 1Tbyte drives into my SMEServer v7.4 as a raid pair for backups. Made good use of the LVM How-To (again!)
Obviously installing the physical drives comes first and they should be recognised by the bios and then as the server booted mine were flagged as /dev/sda and sdb respectively.
Because these are new drives and I am adding them rather than modding the current drives I am working in the normal console.
>p –print the current state (should show as blank)
>n –add a new partition
>p –primary partition
>1 –partition number
>t –change the type or id of the drive
>hex= fd –change to Linux raid
>p –print again the details and shows now as approx 1T lvm partition
>w –write the partition table and exit
repeat for /dev/sdb
#shutdown -r now
Restarting the server should automatically match the two drives as a raid pair. Check by reading through
for something like this:
md: Autodetecting RAID arrays.
md: could not bd_claim hda1.
md: could not bd_claim hda2.
md: could not bd_claim hdb1.
md: could not bd_claim hdb2.
md: autorun …
md: considering sdb1 …
md: adding sdb1 …
md: adding sda1 …
md: created md3
raid1: raid set md3 active with 2 out of 2 mirrors
md: … autorun DONE.
Next check what is showing for LVM
PV /dev/md2 VG main lvm2 [186.19 GB / 64.00 MB free]
PV /dev/md3 lvm2 [931.51 GB]
Total: 2 [1.09 TB] / in use: 1 [186.19 GB] / in no VG: 1 [931.51 GB]
shows my new pair ready for inclusion in the LVM volume groups and logical volume.
Here I ran into an annoyance with a message Insufficient Extents.
I figure I want the whole disk and the above indicates 931.51G is free
lvm> lvcreate /dev/backups -L931.51G -n backups
CTRL-c detected: giving up waiting for lock
Rounding up size to full physical extent 931.51 GB
Insufficient free extents (238466) in volume group backups: 238467 required
I have since learnt that lvm does some rounding and that using the ‘byte’ size is not the best option.
— Volume group —
VG Name backups
Metadata Areas 1
Metadata Sequence No 8
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 0
Open LV 0
Max PV 0
Cur PV 1
Act PV 1
VG Size 931.51 GB
PE Size 4.00 MB
Total PE 238466
Alloc PE / Size 0 / 0
Free PE / Size 238466 / 931.51 GB
VG UUID #######################
In the above screen the important bit is the “Total PE 238466” which tells me the Physical Extents available.
Changing my command to create the lv so that I use the PE rather than byte value
lvm> lvcreate /dev/backups -l238466 -n backups
Logical volume “backups” created
gives a successful outcome.
ACTIVE ‘/dev/main/root’ [184.19 GB] inherit
ACTIVE ‘/dev/main/swap’ [1.94 GB] inherit
ACTIVE ‘/dev/backups/backups’ [931.51 GB] inherit
Next to format the new backups volume
Add the journalling
#tune2fs -j /dev/backups/backups
Edit fstab to add the mounting of this drive by inserting this line
/dev/backups/backups /backups ext3 usrquota,grpquota 1 1
and create the mount point – in my case – /backups
Then one final restart of the server to see that it all starts ok and its done.