Messages in this thread | | | Subject | Re: Volume Managers in Linux | Date | Tue, 03 Nov 1998 20:34:28 -0500 | From | "Brandon S. Allbery KF8NH" <> |
| |
In message <19981103181157.A17442@enchanted.net>, Aaron Wrasman writes: +----- | The filesystem has nothing to do with it. All LV gives you on AIX is a way to | lay things out on multiple physical disks. LVs are just part of a volume grou +--->8
The AIX JFS has a *lot* to do with it, because you can resize (well, expand) JFS filesystems from LVM and JFS will immediately make use of the space. This implies that JFS handles its own allocations in such a way that it can integrate new logical extents into itself "on the fly". And I *do* mean "on the fly" --- you don't have to unmount/take the filesystem offline before extending it, a fact which was very useful when I had to increase the size of / on several CEDA machines recently. JFS picked up on the added space immediately.
In short, AIX LVM works well because JFS is tightly integrated with it.
Certainly you can manipulate non-JFS partitions with LVM and it will "work" --- but e.g. Oracle will never make use of additional extents you add to one of its volumes. Nor will its own internal space allocation be aware of how the LVM is reorganizing, duplicating, etc. its data. Neither would a hypothetical ext2fs implementation for AIX, unless it were redesigned to work with LVM (and it would not work well without a significant redesign, I suspect).
This is why we need better communication between any LVM layer and the next layer up. (Imagine Oracle for Linux knowing how to work with an LVM. I'm pretty sure Oracle for AIX doesn't, but Oracle would have (a) the LVM source and (b) the ability to work with us to insure the LVM design would fit well with Oracle's raw volume management.)
-- brandon s. allbery [os/2][linux][solaris][japh] allbery@kf8nh.apk.net system administrator [WAY too many hats] allbery@ece.cmu.edu carnegie mellon / electrical and computer engineering KF8NH Kiss my bits, Billy-boy.
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |