DRL not working on mirrored volumes in VVR - RVG (Mirrored volume doing full resync of plexes)
I think I am hitting a major issue here with a mirrored volume in RVG. SRL is supposed to provide the DRL functionality . Hence DRL logging is explicitly disabled when a volume is added to RVG. However my testing shows that DRL is not working and in the case of a mirror plex out of sync due to a server crash etc, full resync of mirror plexes is happening. (not just the dirty regions). Here is a quick and easy way to recreate the issue: My configuration: Infoscale 8 Redhat 8.7 I have a mirrored volume sourcevol2 (2 plexes) which I created like below: #vxassist -g dg1 make sourcevol2 1g logtype=dco drl=on dcoversion=20 ndcomirror=1 regionsz=256 init=active #vxassist -b -g dg1 mirror sourcevol2 I wait for the synchronization to complete #/opt/VRTS/bin/mkfs -t vxfs -o nomaxlink /dev/vx/rdsk/dg1/sourcevol2 # mount /dev/vx/dsk/dg1/sourcevol2 /sourcevol2 I create SRL as below: #vxassist -g dg1 make dg1_srl 1g layout=concat init=active I create primary rvg as below: #vradmin -g dg1 createpri dg1_rvg sourcevol2 dg1_srl Verified dcm in dco flag is on. #vxprint -g dg1 -VPl dg1_rvg |grep flag flags: closed primary enabled attached bulktransfer dcm_in_dco Added secondary #vradmin -g dg1 addsec dg1_rvg primarynode1 primarynode2 Started initial replication #vradmin -g dg1 -a startrep dg11_rvg primarynode2 Verified replication is uptodate #vxrlink -g dg1 -T status rlk_primarynode2_dg1_rvg VxVM VVR vxrlink INFO V-5-1-4467 Rlink rlk_primarynode2_dg1_rvg is up to date Here is the actual scenario to simulate mirror plexes out of sync : On primary: Run a DD command to put some IO on sourcevol2 #dd if=/dev/zero of=/sourcevol2/8krandomreads.0.0 bs=512 count=1000 oflag=direct In another terminal , force stop the sourcevol2 while dd is going on. #vxvol -g dg1 -f stop sourcevol2 #umount /sourcevol2 Start the sourcevol2 #vxvol -g dg1 start sourcevol2 #vxtask -g dg1 list -l Task: 160 RUNNING Type: RDWRBACK Operation: VOLSTART Vol sourcevol2 Dg dg1 Even though I only changed only few regions on the sourcevol2 (sequential writes of 512b), the volume goes through a full plex resync (as indicated by the time to start the volume). Summary: DRL on a Volume added to an RVG is not working . Hence mirrored volumes are going through a full plex resync as opposed to only resync of dirty regions.Does Infoscale Storage (VVR) support cascaded space-optimized snapshot?
Configuration: Infoscale Storage 8.0 on Linux Infoscale storage foundation supports cascaded snapshot using vxsnap infrontof= to do cascaded snapshots Infoscale storage (with Volume replicator) documentation doesn't describe cascaded snapshot. I checked manpage for vxrvg. Does not have an infront of attribute. Does that mean cascaded space-optimized snapshots are not supported/permitted on RVG?