EMC metaLUN online expansion

[Mike Barron_3]

We have recently purchased an EMC DMX 1000 for our data center. One of the key features EMC was telling us is that you can expand a MetaLUN already assigned to a volume group on the fly. i.e, c*t*d* is currently 35.5 Gb and with the EMC tool we can expand that MetaLUN to let's say 43.5 Gb. We did this and for 1 it erases everything in the file system using that LUN. and 2. We cannot find a way for that volume group to recognize the new size unless we delete it and recreate it. Question is if EMC says they can do this dynamically, I say How? Does anyone have any experience in this?

[Angus Crome]

I can't answer the first question, as I have no DMX experience "Yet". I would say there are some missing options to your command, that tell it to expand the stripe and/or mirror without initialization.

As to the second question. This is not a limitation of the EMC. HP-UX (LVM) creates the maximum size of a physical volume at creation of the volume group, and it cannot be modified after the fact. You can create it for growth (by assigning larger values to the Physical Extent (PE) size and/or Max PE in a volume). However, this is really pre-configuring your VG for larger volumes.

It is probably not so restricted under JFS 3.3 or Veritas.

[CDI Support · Accepted solution]

MetaLun expansion will not be recognized by the O/S because LVM does not have that capability. EMC has released PowerPath version 4.x with 4.2 being the latest version. This version has a volume manager that can be used to expand the lun on the fly. This volume manager is similar to that of veritas volume manager.