Repartition hard drive w/o losing data, centOS 5

sir-lancealot · 06-03-2008, 10:27 PM

We have a nice EMC box as our file server connected via fibre to our server. It had 4 750gb drives, with one virtual disc pool, and one 2tb partition. I just added 4 more drives to the disc pool now shows 4t, and I want to add to that partition.

I compare it to a desktop I could boot, run gparted and be done, but this is a server I can't take down, I can unmount that device but not sure on the command line side both what app to use as well as the context to resize.

Thanks,
Lr

MensaWater · 06-04-2008, 05:30 PM

What kind of EMC? Symmetrix? Clariion? Celera? Which model?

What software are you using on the host to interact with the EMC? PowerPath? Navisphere? Both?

What filesystems are you using? ext3? reiserfs? vxfs?
Have you checked the limitations of the filesystem? We found here (on UNIX) that we couldn't really extend vxfs (a commercial filesystem from Veritas) beyond on 1.9999 TB.

sir-lancealot · 06-05-2008, 09:58 AM

It's an EMC clarion box.

It's connected via powerpath, so it's mounted as that device, I did use navisphere to add the new drives to expand the disc pool, now according to my dell rep, if it was windows they would use a partition application to resize the parition to add the new space.

It is formatted ext3, as I said if I could just reset the box to a live knoppix or something I could use gparted and make it happen but I can't. So I have to unmount it then at the command line say partition x had 2T, extend it to 4T now (in laymens terms)

Thanks again

MensaWater · 06-05-2008, 10:51 AM

This from "man resize2fs" suggests that you can do an online resize with fdisk (or lvextend if using LVM) THEN doing the resize2fs.

Quote:

The resize2fs program does not manipulate the size of partitions. If you wish to enlarge a filesystem, you must first make sure you can expand the size of the underlying partition first. This can be done using fdisk(8) by deleting the partition and recreating it with a larger size or using lvextend(8), if you're using the logical volume manager lvm(8). When recreating the partition, make sure you create it with the same starting disk cylinder as before! Otherwise, the resize operation will certainly not work, and you may lose your entire filesystem. After running fdisk(8), run resize2fs to resize the ext2 filesystem to use all of the space in the newly enlarged partition.

Haven't done this (fdisk resize without a reboot) myself and it sounds a bit scary to me. I'd certainly do a full backup before attempting it. I'd also schedule it for a period where downtime wasn't as much an issue.

I have done lvextend and extendfs (the equivalent of resize2fs for HFS and VxFS filesystems) on HP-UX dozens of times without issues but never to the size you're attempting. This means there's nothing wrong IN THEORY with resizing filesystems that are live but without having done it on ext3 I can't guarantee it would work.

Also you might want to research the limits of ext3 - as noted before I've seen an effective limit just below 2 TB on VxFS on another platform and wouldn't be surprised if ext3 has a similar limit.

Of course you might avoid all this by adding the 2 TB as a new device instead of adding it to the existing one.