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EVA6000 Will the UUID will run out

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Vasudev Nagarajan_1
Occasional Contributor

EVA6000 Will the UUID will run out

Hi.

I am about to embark on a replication scheme using snapshot / snapclone of HP EVA using SSSU. (Creating Vsnaps and deleting older ones in a cyclic fashion)

I can force the Lum WWWN name to a set that I can obtain and re-use them. However the UUID seems to be not under my control.

Will I run out of UUIDs over a period of time.

Please share your experience and I appreciote your advise/suggestions and comments.
THANKS
5 REPLIES
S Swadesh
Occasional Visitor

Re: EVA6000 Will the UUID will run out

No you would not. You can create maximum of 1024 LUNS on EVA6K. VDISK, Snapshot, snapclone are counted as one LUN.
Uwe Zessin
Honored Contributor
Solution

Re: EVA6000 Will the UUID will run out

He is talking about 128-bit UUIDs (Universal Unique IDentifiers), which are used as persistent handles to identify objects within the EVA, not storage objects. Whenever you create a new virtual disk, for example, it gets a new UUID.

Part of the UUID for storage objects is taken from the EVA's back-end port WWNs (with some bit twisting to mark it as an extended WWN identifier), but the usage of the remaining bits is not documented.

From looking at some UUIDs it looks like it is a 48-bit counter (allowing for 281,474,976,710,656 values), because the lowest 16 bits seem to be 0000 in all cases, but my guess could be wrong. Even if the counter has reached the max. value, there is a chance that it just wraps around.
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The Spartan
Trusted Contributor

Re: EVA6000 Will the UUID will run out

My opinion -
1. Will I run out of UUIDs over a period of time - NO
The aforesaid author is right in hi explanation of UUIDs. Am not aware of specific numbers, but for all practical puroses u wont run out of UUIDs
If you are keen to win, you should be willing to lose.
The Spartan
Trusted Contributor

Re: EVA6000 Will the UUID will run out

Just to add some numbers which am told -

1. You can create a maximum of 16 snapshots per vdisk.
2. max. no of objects-
Vdisks + snapclone + snapshot < 1024
If you are keen to win, you should be willing to lose.
Vasudev Nagarajan_1
Occasional Contributor

Re: EVA6000 Will the UUID will run out

Thanks to all who responded - I have been running snapshots creating new LUNS (about 4) each hour sincce Sep 2006 and I have not Run out of the UUID

Many thanks