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Confused about Snap VP. . .
All:
I have read all the documents I can get my hands on concerning Snap VP, but I am confused. The documentation says that Snap VP shares allocations in the same thin pool between source and target devs.
I just established a new session using the following command:
symclone -g establish DEV001 sym ld DEV002 -full -vse
Why is it taking forever to "copy" when I query this? What is it copying?
Thanks!
LBM99
119 Posts
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July 1st, 2014 12:00
Hi Brandon,
VP Snap targets share tracks between themselves, not with the source volume. If you see a doc that says source and target share allocations, it is incorrect and should be corrected.
VP Snap sessions are “nocopy” sessions, aka copy-on-write sessions. Tracks will only copy to target to preserve that point in time as source tracks are written to.
Mike
AranH1
2.2K Posts
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July 1st, 2014 12:00
Can you post your symlcone list or query output?
BRiley1
53 Posts
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July 1st, 2014 12:00
Well that certainly clears it up. I went back and read the docs, and they are correct. I just read them wrong.
Thanks!
BRiley1
53 Posts
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July 2nd, 2014 11:00
It never gets above 98%, and takes a few hours to get there. No idea why, since it's only got 30GB of data.
AranH1
2.2K Posts
1
July 2nd, 2014 13:00
I thought that was what you were looking at. The output can be a little confusing for VP Snaps, but that is behaving as designed. There is not actual synching of data from source to target because it is a VP Snap and is a CopyOnWrite device.
See the KB article below for an explanation on the output above:
91681 : symclone query command for VP Snap session reports data has copied even though source has not been updated.
https://support.emc.com/kb/91681
AranH1
2.2K Posts
0
July 2nd, 2014 13:00
The activation is immediate. As soon as the command completes the VP Snap is active and you can mount it to a host. If that is a snap of an existing VMFS volume you may need to resignature it before you can mount it.
AranH1
2.2K Posts
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July 2nd, 2014 13:00
... that article was actually written by Michael Bresnahan who replied to you earlier. So you know it is solid :-)
M_Salem
213 Posts
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July 2nd, 2014 13:00
So it is a VMFS, cool. What is the ESXi version? Are you trying to repsent it to the same host?
If yes, have you checked the settings for : LVM.DisallowSnapshotLun and LVM.EnableResignature?
Technically speaking, the device should be available for use once you activate the session so the issue you currently have is more related to VMware than VP SNAP
Hope that helps
Mohammed Salem
M_Salem
213 Posts
1
July 2nd, 2014 13:00
Hi Brandon,
I am not sure if you read this Whitepaper but it will definetly give you further understanding of how VP snap works
http://www.emc.com/collateral/hardware/white-papers/h10498-timefinder-vp-snap-local-repl-wp.pdf
Hope that helps
Mohammed Salem
BRiley1
53 Posts
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July 2nd, 2014 13:00
Thanks guys. So how long does an activation take then? I've been waiting a while, and I still cannot see a VMFS on the TGT LUN in question.
BRiley1
53 Posts
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July 2nd, 2014 14:00
BRiley1
53 Posts
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July 2nd, 2014 14:00
Yes. This is my TGT for this session.
First I created my DG, and added my source device.
Then I added 0703 with:
Symld –g LAB1TF –sid 543 add dev 0703 –tgt
Then I ran:
Symclone –sid 543 –g LAB1TF create –vse DEV001 sym ld TGT001 –nop
and:
Symclone – sid 543 –g LAB1TF activate DEV001 sym ld TGT001 –nop
And that's it.
I'm running:
Microcode Version (Number) : 5876 (16F40000)
Microcode Registered Build : 28
Microcode Date : 12.02.2013
Microcode Patch Date : 12.02.2013
Microcode Patch Level : 251
Symmwin Version : 161
Enginuity Build Version : 5876.251.161
Thanks!
AranH1
2.2K Posts
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July 2nd, 2014 14:00
The fact that there are no written tracks doesn't mean anything as you have not written to the VP Snap device yet.
I would try rescaning the ESXi host for disks and VMFS volumes again to make sure it is looking at the volume correctly.
M_Salem
213 Posts
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July 2nd, 2014 14:00
Just need to confirm, this is your target VP SNAP device ?
If yes, then we cannot blame VMware on identifying the disk as blank as the total written tracks here is zero.
Now I need you to share with us the exact syntax of commands you used to create a VP snap of your src device 06fb
Also, what is the ucode you array running?
Hope that helps
Mohammed Salem
M_Salem
213 Posts
0
July 2nd, 2014 14:00
You followed the correct procedures. So at this moment, I would like to ask you if you can copy any file (may be iso) or create a vmdk on the src device (vmkfstools or any other GUI tool).
Next, check the symcfg list -tdev -range command again (You should see some written tracks there) afterwards rescan your host HBAs , try to mount the device and update us with the result.