EVA8100, ADD MULTISNAP SNAPSHOT... and containers

[Adam Garsha]

It looks like you need containers to make use of "ADD MULTISNAP" to get consistent group of snapshots. If using snapshots (not snapclones), do the containers have to be fully allocated size? i.e. what if I only expect about 1-5% copy-on-write activity? Can I create some 10% containers and use them for multisnaping a bunch of logically related LUNs?

Basically: must the containers be fully allocated in size; i.e. same size as source LUNs to make use of snapshots.

Much thanks,

[Uwe Zessin · Accepted solution]

A container is something like a virtual disk without data contents - no 'thin-provisioning', sorry.

This idea of a container is to pre-allocate storage and save time on deletion / re-allocation after a new object creation (traditional /full snapshot, snapclone, mirrorclone).

[Adam Garsha]

points will come.

Yes, I understand on containers, and I am thinking you are saying "no luck". But just to be sure my point is clear,

If your snapshot set will be short-lived (e.g. just to pull backups to tape and then it will be thrown away) then the container is just a place for copy-on-write activity during the lifetime of the snap. In my case, I've got a collection of low-activity gi-normous LUNs that I want to snap, but I don't want to preallocate gi-normous containers since I will be throwing away the snaps after only about 2% Copy-on-write activity and since I just plain don't have that much disk (but I need a consistent group).

It seems for multisnap, probably to facilitate the consistency group timing, containers seem to be required whereas for a single lun "add snapshot", it is not required. Maybe multisnap isn't really all-at-once... but as-best-as-possible serial "ADD SNAPSHOT"--hope-not but that is secondary to my question.

I think I'll try it, but I want to see if I create containers that are for example 100GB in size for each low activity 1TB LUN that I need to snapshot (not snapclone) if I can then multisnap (or whether I NEED 1TB containers for each LUN).

In short, I am asking if my containers can be smaller then the source LUN when using short-lived snapshots (in leau of snapclones).

[Uwe Zessin]

> short-lived snapshots

The EVA does not care. Last time I checked, you could only map a traditional (=full capacity) snapshot to a container with the same size as the original virtual disk.

Why not create two small 2GB vdisks and two 1GB containers and try it out? (sorry, I don't have access to an EVA with recent firmware right now to try it on my own).

[Adam Garsha]

I don't have access until Monday, but I'll try it out and post and points.

[Adam Garsha]

I haven't forgotten. Got sidetracked. I'll look in a few minutes after I put out a few fires.

[Adam Garsha]

And the verdict... no luck. I created 2 10GB vdisks (very_temp_3, very_temp_4) and 2 1GB containers (very_temp_1, very_temp_2) and I couldn't get a demand-allocated snapshot:

cell-c2> add multisnap vts3 vdisk="very_temp_3" container="very_temp_1" snapshot vts4 vdisk="very_temp_4" container="very_temp_2" snapshot

Error : vts3 Attribute mismatch
Error : vts4 Attribute mismatch
Error: Error an internal operation failed. Trace information provides more information. [Attribute mismatch]

"Attribute mismatch". If I increase containers to 10GB, it works fine. Bummer dude.

[somashekhar.r]

a

[somashekhar.r]

This could be MLD issue , approach HP support