topic Re: Resize Limit Hit in ONTAP Discussions

Resize Limit Hit

N_ANDREEV — Thu, 05 Jun 2025 05:59:10 GMT

So we've hit the resize limit for a LUN:

lun resize: New size exceeds this LUN's initial geometry

Now what options do we have? SnapMirror won't help, because the replicated LUN will have the same geometry. Are there any other ways to transfer data to a new LUN, except for the simple robocopy?

Re: Resize Limit Hit

ASHWANI8HIGHS — Thu, 04 Jul 2013 05:00:49 GMT

Use ndmpcopy for data transfer

Re: Resize Limit Hit

N_ANDREEV — Thu, 04 Jul 2013 05:18:38 GMT

I'm assuming that to accomplish this, I will need to power off the server, copy the LUN using ndmpcopy and reconfigure. It's a 2TB LUN. So it will take a considerable amount of time to copy. Is there any way to make an outage shorter?

Re: Resize Limit Hit

ASHWANI8HIGHS — Thu, 04 Jul 2013 05:39:28 GMT

Copy speed will depend on source and destination distance .

Yes you can do it minimum outage .

1) Start with ndmpcopy 0 level

2) Once your data is copied using level 0 ndmpcopy use ndmpcopy level 1 & level 2 (if required) for incremental

data written when level 0 was running .

Use level 1 & level 2 copy at the time when there is no or minimum data being written on lun . After level 2 i hope the new lun has all the data of old lun and then mount the new lun on server

Re: Resize Limit Hit

N_ANDREEV — Thu, 04 Jul 2013 06:40:38 GMT

Will try that and share the result. Thanks.

Re: Resize Limit Hit

Darkstar — Thu, 04 Jul 2013 12:22:59 GMT

ndmpcopy will almost certainly not work, because it copies the LUN geometry as well, so the new LUN will have the same geometry (and limitations) as the old one.

Your only option is to do the copy on the client (i.e. create & map a new LUN, copy all data over from the client, unmap & delete old LUN) [*]

To avoid this in the future, always create your LUNs with 2TB size and immediately resize them down to your desired size. In that case the initial size (2TB) will be used for the geometry and everything will be fine.

-Michael

[*] There is an undocumented way to change the LUN geometry which would allow you to resize it even further, but in that case you have to be absolutely sure that nothing on that LUN uses the old C/H/S addressing scheme but only LBA. Otherwise you will lose data.

Re: Resize Limit Hit

ASHWANI8HIGHS — Thu, 04 Jul 2013 13:17:14 GMT

What about creating a new lun and then using ndmpcopy for data transfer .

Re: Resize Limit Hit

Darkstar — Thu, 04 Jul 2013 13:51:21 GMT

I don't understand your question. ndmpcopy works on WAFL level, not on the filesystem inside the LUNs.

Or do you mean installing an open source ndmp copy tool inside the client and using that to transfer the data? In that case it would be easier to simply use robocopy (Windows) and/or rsync (Linux/Unix)

Re: Resize Limit Hit

N_ANDREEV — Fri, 05 Jul 2013 00:31:51 GMT

Thanks for sharing this. I'm lucky I haven't started the migration yet. DataMotion won't help me here either, will it?