Adding code to allow users to split legs off of a mirror wasn't all that hard. However, I could use some help regarding the nature of the arguments that should be used to invoke this action. The following patches introduce a new (horrible) argument '--split' to lvconvert that signals the intent to split and keep a desired leg of a mirror. Example run: [root@bp-01 ~]# lvcreate -m2 -L 500M -n lv vg Logical volume "lv" created [root@bp-01 ~]# lvs -a -o name,copy_percent,devices LV Copy% Devices LogVol00 /dev/sda2(0) LogVol01 /dev/sda2(4451) lv 100.00 lv_mimage_0(0),lv_mimage_1(0),lv_mimage_2(0) [lv_mimage_0] /dev/sdb1(0) [lv_mimage_1] /dev/sdc1(0) [lv_mimage_2] /dev/sdd1(0) [lv_mlog] /dev/sdi1(0) [root@bp-01 ~]# lvconvert -m1 --split vg/lv /dev/sdc1 Logical volume lv converted. [root@bp-01 ~]# lvs LV VG Attr LSize Origin Snap% Move Log Copy% Convert LogVol00 VolGroup00 -wi-ao 139.09g LogVol01 VolGroup00 -wi-ao 9.81g lv vg mwi-a- 500.00m lv_mlog 100.00 lv_mimage_1 vg -wi-a- 500.00m You can see from the above that I went as far as to specify the leg I wanted split off. Aside from the new '--split' argument not being very good, we also end up with a new logical volume named, 'lv_mimage_1', which also isn't very good. Should I change the name via s/_mimage_1/-copy-%d/, or should I allow the name to be specified (or left alone)? Here is the current syntax and some others I have thought of: # New '--split' argument. # This is suppose to give the user the ability to signify a split # of the mirror, rather than a reduction/increase in mirror images. # However, something like '--keep_images' might better signify that # although we are reducing the number of mirror legs, we want to # have them presented rather than removed. prompt> lvconvert -m <n> --split vg/lv <removable device(s)> # New '--splitmirror <n>' argument # Replaces '-m <n> --split', and rather than specifying the number # of legs you want remaining in the mirror when finished, you specify # the number of legs you want split off. # # BTW, you can only split off one leg at a time right now, but I # don't see a reason why we couldn't split a 4-way mirror into # 2 2-way mirrors at some point in the future. (Being able to # specify the removable devices also allows us to choose every # other device if we chose to.) prompt> lvconvert --splitmirror 1 vg/lv <removable device(s)> Please added better ideas if you have them... I am leaning toward the second example (even though I implemented the 1st in the patches). Concerning the naming of the newly split off device, we could use the '-n <name>' argument. If unspecified, we would have to choose some default. brassow -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
