Unix and file systems and logical volumes

[Jim Tropiano_1]

Just wnat to make sure that I am thinking of this right.
If I have a files system within some volume group. CAn I extend it accross two logical volumes? I do not think I can but just wanted to be sure.
have a CX700 - create metalun , configured them on the Hp9000. Now need to increate the metalun. here is what my choices I think...
1) create new metalunon cx700
2) present disc to rp7420
3) do a vgextend to the exisitng volume group
4) do a lvextend on the logical volume to add space
5) then do a extendfs...

What I would like to do is extend the fs over mulitple logical volumes can I do this

[Geoff Wild · Accepted solution]

No - you can't have a filesystem span a locical volume...

What you do is extend the lvol, then increase the filesystem.

Rgds...Geoff

[Doug O'Leary]

Hey;

No, you cannot extend 1 filesystem across multiple logical volumes. The process you outlined above is correct.

HTH;

Doug

[Pete Randall]

There is a one to one ratio between logical volumes and file systems (unless the logical volume is used as a raw LV - like for databases).


Pete

[Simon Hargrave]

No, as you say you must publish an extra LUN, vgextend the group, lvextend the logical volume then extend the filesystem.

Why would you want a filesystem spread on multiple logical volumes anyway, performance? For this you should either publish LUNs such that there are no hot spots in your array to your volume group, alternatively spread your data (assuming this is for database files) over separate filesystems.

[Hakan Aribas]

You cannot extend a file system over multiple logical volumes. If you need extend your file system, you have to extend its logical volume. For more information please look at the following link:

http://docs.hp.com/en/B2355-90672/ch03s07.html

[DCE]

You cannot extend one file system across logical volumes.

You can however, mount one logical volume under another.

ie

/dev/vg01/lvol02 = /database
/dev/vg01/lvol03 = /database/archive

[TwoProc]

Jim, you can't extend a single fs over multiple logical volumes. But, YOU CAN extend a single file system over multiple *pvs* .

You can create your luns (I'm assuming since you said metalun your doing some SAN work), and then add all of those luns to your volume group, then you can extend your file system across the volume group using whichever pv's (mapped to LUNS) you wish.

Is this what you're trying to accomplish?

LUN1.....LUN2.....LUN3
..|...........|................|
PV1.....PV2........PV3
..|...........|................|
..-------------------------
...............|
............VG220
..............|
...........LVOL1
..............|
.../yourfilesystem

[Jim Tropiano_1]

Thanks
I kindof knew. But just wanted to see if there was a different way to do what we wnated to do. Thanks again.

[Jim Tropiano_1]

That is what the picture would look like.

I waws just hoping for a different way to add space as needed.