Symsnapvx is VMAX3’s replacement of legacy clone. Symsnapvx essentially removed the need to manage clone target devices and groups as the snaps are not given a target device unless they need to be mounted (linked). Additionally by default the physical space used by Symsnapvx will be less than an equivalent implementation on a VMAX2.
The basis of Symsnapvx is to take snaps of Symmetrix LUN’s. These will automatically be given a generation number and a Time to Live (TTL) can be set. By default, no copy will take place unless a track is modified on the source in which a copy will be taken to keep the snaps point in time accurate, Copy of First Write.
If the snap is needed it can be “linked”. After a snap is linked the snap will be given a symmetrix device ID which can be masked and accessed by hosts. Once again no copy is needed, the -copy option can be used to get a full copy of data on the link target device. this is not needed however.
After linking the device can be accessed immediately by the host. Any data changed on the linked devices will be stored in the SRP against the link target.
other operations are expected as seen in legacy clone.
Establish / start a snap
symsnapvx -sid xxxx establish -f snapvx.txt -name backup_17sep2015
Snapvx.txt is the dev_file here. You only need the devices you are snapping- no targets needed.
Display snap file
symsnapvx -sid xxxx -f file.txt list
Add -detail for more info
Generation 0 will always be newest snap. The bigger the generation, the older the snap
symsnapvx -sid xxxx -f snapvx.txt set ttl -delta 1 -snapshot_name testbackup
This does the TTL for ALL generations. add a -generation x to specify a specific snapshot otherwise all gens will take it. Delta needs to be <400 and once you set it i dont know how to remove it.
Linking a snapshot
symsnapvx -sid xxx -f snapvx.txt link -snapshot_name backup_17sep2015
here the snapvx.txt is different. we need both source and target devs (like old clone)
Displaying linked devs
symsnapvx -f snapvx.txt list -linked
without the -linked you wont see the ‘targets’
This will roll the existing link target back to the point in time of the original snap. Any Existing data on the link target will be returned to the SRP.
symsnapvx -sid xxx -f snapvx.txt -snapshot_name backup_17sep2015 relink
This will remove the linked relationship. The
symsnapvx -sid xxx -f snapvx.txt -snapshot_name backup_17sep2015 unlink
This will restore an existing snap back to the source device.
symsnapvx -sid xxx -f snapvx.txt restore -snapshot_name backup_17sep2015 -gen 1
symsnapvx -sid xxx -f snapvx.txt terminate -snapshot_name testbackup
Terminate with the above command will terminate the youngest snapshot (Gen0). you need to specifiy with the -generation x flag to tell CLI when snapshot to delete. dont know how to delete all yet