PedalHarder
3 Argentium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

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?

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PedalHarder
3 Argentium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

You will see in my example there is just a single establish. The relink will obtain a new PIT and produce a copy delta. So I think in your case, the second establish isn't required and this is causing another full copy. From the TF CLI prouct guide:

RELINK:

Remove the link to target device and present a different snapshot from the same source device, or relink to

the same snapshot. Refreshes the point-in-time copy on the link target when it's been modified by host

writes.

I think when it says "...when it's been modified by host writes" actually means when the source or target has been updated. In other words the relink will make the target device the same as the source. The wording is a little unclear.

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echolaughmk
3 Zinc

Re: Reproduce TimeFinder/Clone functionality on VMAX3

From previous testing (don't have a box right now), I was seeing incrementals I believe with new establishes on the source volume to create the new PiTs (like ProtectPoint) like dynamox is doing so I think I would expect it to work incrementally as long as the relink is used and the source stays the same. that snippet above seems to state both will be incremental:

RELINK:

Remove the link to target device and present a different snapshot from the same source device, or relink to

the same snapshot. Refreshes the point-in-time copy on the link target when it's been modified by host

writes.

It's odd that you are seeing a full copy, If you re-run a test and use the -detail at the end on the list, does it show you a number of shared and non-shared tracks between your generations since I am assuming you will have 2 generations if you are using the same source and snapshot name. Just curious if that gives any insight.....

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dynamox
6 Thallium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

Jasonc,

If i relink to the same snapshot over and over and look at the output from this command

symsnapvx -sid 123   -sg sg_oracle list   -linked -detail -gb


remaining GB column always starts out by showing 200G remaining. (200G is my device size).  Snapshot has not changed, target devices are not presented to any hosts, then there should be nothing to copy, it should be done instantly.  What am i missing ?


Thank you

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PedalHarder
3 Argentium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

Let me redo my test using the same query format you use and see what i get.... Next week most likely.

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PedalHarder
3 Argentium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

I have rerun the same test i did before using a device file and also using storage groups as in your jobs Dymox. The initial link performs a copy operation. Subsequent relink operations produce no data to copy since I havent updated the source.

I had non RDF and RDF1 type devices in the lnsg.

I note that the RDF1 devices that are the linked target need to be suspended before the relink -copy can work. As an added check, doing an  RDF query after the relink showed no RDF invalids.In other words, i cant recreate your scenario unfortunately. Everything I do seems to be in alignment with what is documented.  You many need an SR...

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dynamox
6 Thallium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

Jasonc,

I am working with support on this. They are trying to re-produce this in the lab but what they leaning towards is that it's a reporting issues in symcli.  I did more tests over the weekend:

source device is 200G, all Flash VMAX

1) create snapshot

2) "link -copy"  - took 5 minutes to complete according to "list -linked -detail"

3) "relink -copy" (snapshot has not changed) - took 1 minute to complete according to "list -linked -detail"

So from this it looks like it's an incremental "copy".   That raises questions:

1) Why did it take 1 minute to determine that nothing changed ?

2) So now there is absolutely no reliable way to determine how much "incremental" change to be copied to target ?

3) Counters displayed during "list -linked -detail" are bogus, they are not presenting true rate, invalid tracks owned to target.

Thoughts ?

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dynamox
6 Thallium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

Jasonc,

Take a look at fixes 83953 and 84247.

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PedalHarder
3 Argentium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

OK, thanks, well both of these fixes are on the box I used for testing. I can see that they are linked to an SR that is similar to your scenario, so I think your process should work as designed with these fixes.

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dynamox
6 Thallium

Re: Reproduce TimeFinder/Clone functionality on VMAX3

good, they will be installed on my VMAX3's very soon.

Do you know how VMAX3 calculates what's needed to be copied to target device during relink -copy command ? I know it does not rely on delta between two snapshots.

Thank you

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