Hi All.
Currently I am trying to change a logical volume from linear to stripped because I would like to have a better write throughput. I would like to perform this change "live" without stopping access to this lv.
I have found two interesting examples: http://community.hpe.com/t5/System-Administration/Need-to-move-the-data-from... http://www.depesz.com/2015/10/08/converting-logical-volume-so-that-its-strip... Both say basically to: - change the lv to a mirrored one by adding a stripped copy (~second device in RAID1) - change it back to a non-mirrored one by removing the primary linear lv (~first, source device in RAID1)
My os is: $ cat /etc/redhat-release CentOS Linux release 7.1.1503 (Core) $ uname -r 3.10.0-229.14.1.el7.x86_64 $ rpm -qa | grep -i lvm lvm2-libs-2.02.115-3.el7_1.1.x86_64 lvm2-2.02.115-3.el7_1.1.x86_64
And the solution proposed in above examples does not work on it. After (lv xxx is only on /dev/sdb4 before): # lvconvert --mirrors 1 --stripes 4 /dev/cinder-volumes/xxx /dev/sda4 /dev/sdc4 /dev/sdd4 /dev/sdf4 I am getting in "lvdisplay -m":
--- Logical volume --- LV Path /dev/cinder-volumes/xxx LV Name xxx VG Name cinder-volumes LV UUID AKjKAo-66cv-Ygc2-4Ykq-sSJQ-RJOY-mfjoMD LV Write Access read/write LV Creation host, time test.local, 2015-10-28 17:45:28 +0100 LV Status available # open 1 LV Size 64.01 GiB Current LE 16386 Mirrored volumes 2 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 8192 Block device 253:22
--- Segments --- Logical extents 0 to 16385: Type raid1 Monitoring monitored Raid Data LV 0 Logical volume xxx_rimage_0 Logical extents 0 to 16385 Raid Data LV 1 Logical volume xxx_rimage_1 Logical extents 0 to 16385 Raid Metadata LV 0 xxx_rmeta_0 Raid Metadata LV 1 xxx_rmeta_1
And in "pvdisplay -m":
--- Physical volume --- PV Name /dev/sda4 VG Name cinder-volumes PV Size 2.73 TiB / not usable 4.00 MiB Allocatable yes PE Size 4.00 MiB Total PE 715255 Free PE 287476 Allocated PE 427779 PV UUID IrkkwI-AqpP-bTll-vlPq-NDSe-rDUg-ecAnkp ... Physical extent 427776 to 427776: Logical volume /dev/cinder-volumes/xxx_rmeta_1 Logical extents 0 to 0 Physical extent 427777 to 444162: Logical volume /dev/cinder-volumes/xxx_rimage_1 Logical extents 0 to 16385
--- Physical volume --- PV Name /dev/sdb4 VG Name cinder-volumes PV Size 2.73 TiB / not usable 4.00 MiB Allocatable yes PE Size 4.00 MiB Total PE 715255 Free PE 698868 Allocated PE 16387 PV UUID hx0a1v-M68S-aPBL-1x9r-8EiD-3cu3-GQPLRo
--- Physical Segments --- Physical extent 0 to 0: Logical volume /dev/cinder-volumes/xxx_rmeta_0 Logical extents 0 to 0 Physical extent 1 to 16386: Logical volume /dev/cinder-volumes/xxx_rimage_0 Logical extents 0 to 16385 Physical extent 16387 to 715254: FREE
So the migration to a RAID1 logical volume is successful but the stripping (above "lvconvert --mirrors 1 --stripes 4 /dev/cinder-volumes/xxx /dev/sda4 /dev/sdc4 /dev/sdd4 /dev/sdf4") is not taken into consideration because only /dev/sda4 and /dev/sdb4 are used for xxx logical volume afterwards.
Also when I run:
# lvconvert -m 0 /dev/cinder-volumes/xxx /dev/sdb4
afterwards I get xxx logical volume only on /dev/sda4 and it is linear (not stripped).
Can someone help me with this? ;)
BR, Rafal.