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Reproduce TimeFinder/Clone functionality on VMAX3
Hello guys/gals,
I am trying to reproduce TimeFinder/Clone functionality on VMAX3. I would prefer not to use "emulation" and achieve the same thing using symsnapvx. One requirement is that clone target is a fully copy and not just a snapshot. Here are the steps that i am attempting:
1) create target TDEVs same size as source TDEVs, add them to a storage group.
2) create snapshot
symsnapvx -sid 123 -sg sg_oracle -name snap establish
3) link to target TDEV, specify -copy to get full copy
symsnapvx -sid 123 -sg sg_oracle -snapshot_name snap link -copy -lnsg sg_snaptarget
so far so good, i can SRP utilization go up so it's making a full copy.
4) next i need to perform symsnapvx equivalent of symclone recreate. I don't see any options but to establish snapshot again
symsnapvx -sid 123 -sg sg_oracle -name snap establish
5) next i relink to target devices
symsnapvx -sid 123 -sg sg_oracle -snapshot_name snap relink -copy -lnsg sg_snaptarget
So these steps appear to achieve what i typically do with symclone, except for one thing. When i look at snapshots i see two snapshots with the same name. I don't want multiple snapshots, i just need the one that i just established. I can't terminate gen 1 snapshots because that will break "incremental" nature of this approach ? Am i understanding correct ? If that's the case what are my options, setting TTL on each snapshot and let it auto expire after 25 hours or so ?
symsnapvx -sid 123 -sg sg_oracle list -detail
Storage Group (SG) Name : sg_oracle
SG's Symmetrix ID : 0000000123 (Microcode Version: 5977)
------------------------------------------------------------------------------------------------------------------------
Total
Sym Flgs Deltas Non-Shared
Dev Snapshot Name Gen FLRG Snapshot Timestamp (Tracks) (Tracks) Expiration Date
----- -------------------------------- ---- ---- ------------------------ ---------- ---------- ------------------------
000B3 snap 0 .X.. Mon Feb 15 05:03:38 2016 0 0 NA
snap 1 .... Mon Feb 15 04:43:22 2016 0 0 NA
---------- ----------
0
Thoughts ?
Thank you
PedalHarder
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Posted February 14th, 2016 21:00
Edit: relink -copy should provide the function you are after. I see that there are 2 instances of snapshot name "snap" in your output. Let me look at this in more detail....
echolaughmk
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Posted February 15th, 2016 05:00
The relink command is the recreate from my experience since it will incrementally re-sync from the source to the linked target. You would likely create a new snapshot form the prod volume for the updated PiT image and then issue a relink from that snapshot to your existing linked target and it will be an incremental refresh, so your #4/#5 above is the way that I am aware of.There is no recreate that I am aware of with snapvx.....I think your procedure above is correct and the intended process.
Jasonc,
reason i am doing -copy is because target devices needs to be an R1, according to timefinder docs it requires -copy.
As you can see in step 5 i am using relink -copy but how do i "refresh" my snapshot so that it's an incremental copy. I don't see a recreate command for the snapshotvx, i only see establish. When i run establish with the same name as my previous snapshot ..it creates a new one.
echolaughmk
2 Intern
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Posted February 15th, 2016 05:00
I have done both, but tend to do with the manual deletion or script it as cleanup upon creation of a new one just because of preference/control versus anything else really.
echolaughmk
2 Intern
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522 Posts
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Posted February 15th, 2016 06:00
hmm...you have the -copy which is what makes it incremental so I wouldn't expect a full push. Does the -summary listing show anything different?
something is not right. Everytime i run this command:
symsnapvx -sid 123 -sg sg_oracle -snapshot_name snap relink -copy -lnsg sg_snaptarget
even if i did not create a new snapshot, output from "symsnapvx -sid 123 -sg sg_oracle list -linked -detail -gb" shows that it's performing a full copy. Same snapshot, nothing changing, i am simply re-running the same relink command. Any thoughts ?
same thing, shows how much is remaining to copy
symsnapvx -sid 123 -sg sg_oracle -snapshot_name snap list -summary -gb
Storage Group (SG) Name : sg_oracle
Snapshot State Count
----------------------- ------
Restored 0
RestoreInProg 0
Established 2
EstablishInProg 0
Linked 0
CopyInProg 1
Copied 0
NoSnapshot 0
Failed 0
----------------------- ------
Total 3
GB(s)
-------
Total Remaining 157.3
PedalHarder
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Posted February 15th, 2016 19:00
I tested this on a VMAX 3 running SE v8.0.3 and 5877.790 (EMC lab box) using the following:
symsnapvx -sid 89 -name jason establish -dev cd8
symsnapvx -sid 89 -snapshot_name jason link -lndev cd9 -dev cd8 -copy
symsnapvx -sid 89 list -dev cd8:cd9 -summary -gb << This shows non-zero value in GB to copy field
symsnapvx -sid 89 -snapshot_name jason relink -lndev cd9 -dev cd8 -copy
symsnapvx -sid 89 list -dev cd8:cd9 -summary -gb << This shows zero value in GB to copy field
Repeat last two commands numerous times and consistently get zero value in GB to copy. My test appears to be working as designed. What code levels are you running?
PedalHarder
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Posted February 14th, 2016 21:00
I don't think the copy feature of SYMSNAPVX is there to support the legacy CLONE COPY feature. I would be interested to know if there is a technology reason to use COPY (outside cascade operations) with snapvx in your environment.
As I understand it, when using cascade SYMSNAPVX, you have a dependency on terminating the the cascading snaps in reverse order typically (can't terminate the original source>tgt if there are cascades). If the original source>tgt snapvx is set to copy (and all tracks copied), this relationship may be terminated, even if the TGT is a source for a cascaded snapvx.