Disk Install

[Nobody's Hero]

I am installing a jbod with 180GB capacity. 10 36Gbyte drives and I want 10 18 Gbyte filesystems created and mirrored. Looking for recommendations for the layout. I was going to take each 5, 36 Gbyte drives, cut each one in half, and then mirror each logical drive. So I'll have 2 lvols or vgs on each disk. Does this sound OK? Any help appreciated. Also, if someone has the commands handy I'd like to see these, I dont want to use sam.

10x
RPM

[Pete Randall]

Robert,

Each 36GB drive can only belong to one VG so you'll have to use lvols to break it down further to 18GB. Unless you have separate and distinct uses for these 18GB "chunks", I would put them all in the same volume group and then mirror the lvols. Ideally, if you have the ability to have dual path connections to the jbod, you would want to separate primary and mirror on different paths. That's about it.


Pete

[Pete Randall]

Sorry, forgot:

For commands, take a look at the EXAMPLES section of the vgcreate man page. Everything is spelled out there.


Pete

[Patrick Wallek]

I would just create 1 VG with all 10 disks, using an appropriate PE Size, MAX PE per PV, etc., and then utilize PVG's to separate the disks into 2 groups of 5.

Then when you create your LVs and mirror them, you use the PVG-strict option (-s g option to lvcreate, I believe) to make sure your mirrors go on the other PVG.

[Mark Grant · Accepted solution]

Personally, I'd put five of the disks in a physical volume group and five in the another. Then, create all my logical volumes using the first physical volume group but using a PVG-strict allocation policy and then mirror these onto the other five disks.

This makes administering things easier as you can ensure that when you extend logical volumes in the future, you always have the mirrors on seperate disks and you only need to refer to the physical volume group names.

In a nutshell

"pvcreate" on all your disks

Create your volume group by making a directory /dev/vg01 and then "mknod /dev/vg01/group c 64 0x020000" (that 0x02000 must be a unique number for group files in your volume groups).

Then you need to actually crete the volume group with "vgcreate".

Then "vgextend" your group to include all disks.

Then layout your physical volume groups by editing /etc/lvmpvg. This file looks like this

VG /dev/vg01
PVG primary
/dev/dsk/xxxxxx
/dev/dsk/xxxxxx
...
..
PVG mirror
/dev/dsk/xxxxx
....
...

Then create your logical volumes using
"lvcreate -s g /dev/vg01". This will create 0 length logical volume sthat you can then extend into the physical volume groups.

"lvextend -L /dev/vg01/lvol1 primary"

Then mirror the logical volume

"lvextend -m 1 /dev/vg01/lvol1"

This mirror will be built in the "mirror" physical volume group.

Oh, you might want ot put a filesystem on there too

"newfs -F vxfs /dev/vg01/rlvol1"