Hi On Thu, Oct 30, 2014 at 08:15:47PM +0100, b-m...@gmx.ch wrote: > Hi all, > > If I have a LVM which uses two partitions on two different disks and at least > one of its subvolumes is always in use, can the second disk spin > down?
Depends on where that subvolume is mapped to. It will probably be instructive if you run e.g.: # pvdisplay --maps /dev/sda1 which will give the answer to "Which LVs occupy chunks of /dev/sda1?". Or # lvdisplay --maps /dev/vgname/lvname which will give the answer to "Where is vgname/lvname actually stored?" (alternatively, run "vgcfgbackup vgname" and peruse /etc/lvm/backup/vgname) > > An example showing what I mean: > _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ > |/dev/sda1 | |/dev/sdb1 | > |_ _ _ _ _ _ _ _| |_ _ _ _ _ _ _ _| > > > lvmGrp = /dev/sda1 + /dev/sdb1 > _ _ _ _ _ _ _ _ _ _ _ _ _ > |lvm1 | |lvm2 | |lvm3 | > |_ _ _ _| |_ _ _| |_ _ _ _ _ _| > > So since sdb is new, if I add lvm3 it will be on sdb1 and not sda1, > correct?; Assuming that /dev/sda1 is full, yes. Even so, you can force the issue when creating the LV. Or by moving it afterwards. > if I don't mount lvm3 automatically, can sdb spin down although lvm1 and lvm2 > are used? I haven't actually tried that, but I believe so. As long as none of the LVs which reside (even partially) on /dev/sdb1 are in use, yes. Note that most LVM operations (lvcreate, pvdisplay etc) will wake up *all* of the PVs. > The reason for this setup is the possibility to extend e.g. lvm2 later with > space on sdb1 if it is really required without any re-formatting. (Of course > I > will loose the spin down then, but for the time being I'd take care of my new > disk.) Remember that you can move portions of LVs around to suit you if you like (without downtime) - courtesy of the (somewhat misnamed) pvmove command. So even if you start off with the "wrong" layout, it's relatively easy to fix. Hope this helps -- Karl E. Jorgensen -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: https://lists.debian.org/20141030223059.GA24198@hawking