LVM and VxVM

diskinfo doesn't return new size

 
Eric SAUBIGNAC
Honored Contributor

diskinfo doesn't return new size

Bonsoir,


Online JFS : every thing should go well to increase the size of a mounted filesystem. Yes, but ...

For some reasons the filesystem itself is mounted directly from a disk special file, not from an LVM structure. When the size of the corresponding LUN is increased, diskinfo doesn't return the new size until the disk special file is released. That is if I want to deal with the new size, I must unmount the FS before. In other words I can't extend the FS size online ... :-(

It is not a problem with LVM, nor Online JFS : vmunix doesn't return new sizes as long as the correspondig resource is in use. For example, a simple "sleep 3600
Tried many ioscan, rmsf, insf, etc ... no way.

I have an idea about your answers :-( , but I wonder if it could be possible to bypass this behavior : a kernel parameter, a patch, some hidden or missunderstood parameters to commands, features from VxVM, or VxFS, that could release a FS a few sec without unmounting, etc ... ????

I forgot : no way to use the new IO stack from 11iv3 ... OS is 11iv2 and can't be upgraded soon.

Thanks in advance.


Eric
17 REPLIES 17
Torsten.
Acclaimed Contributor

Re: diskinfo doesn't return new size

Some time ago I played around with vgmodify in 11.23:

# saconfig /dev/ciss3 -E 1 -c 100
Logical drive 1 extended from 87.9 GB to 100 GB in capacity

# diskinfo -v /dev/rdsk/c3t0d1
SCSI describe of /dev/rdsk/c3t0d1:
vendor: HP
product id: LOGICAL VOLUME
type: direct access
size: 92159040 Kbytes
...

(not changed)

# umount /user1
# vgchange -a n vg01
# vgmodify -o vg01
# vgchange -a y vg01

# diskinfo -v /dev/rdsk/c3t0d1
SCSI describe of /dev/rdsk/c3t0d1:
vendor: HP
product id: LOGICAL VOLUME
type: direct access
size: 104857600 Kbytes
...

This is what I did. Not sure if vgmodify and diskinfo is related anyhow, but maybe my "umount" did it.

Hope this helps!
Regards
Torsten.

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TTr
Honored Contributor

Re: diskinfo doesn't return new size

I had the same issue. I even rebooted the server but ioscan does not see the new size. What I did not try and I suggest is to remove the mapping for that LUN (unmask or unpresent), run ioscan on the server without the LUN and then remap the LUN to the server as if it is a new disk.
TTr
Honored Contributor

Re: diskinfo doesn't return new size

Eric,

I misunderstood your question in my previous reply. I guess "extendfs" is only LVM aware and not physical disk aware.
Eric SAUBIGNAC
Honored Contributor

Re: diskinfo doesn't return new size

Bonjour,


Torsten, in your example I think IMHO that vgmodify and diskinfo are not related : diskinfo would have returned the right size just after "vgchange -a n vg01". I did this test yesterday before posting : 1 Go LUN created on EVA, ..., vgcreate, vgchange -a y, increase LUN to 2 Go, diskinfo wrong, vgchange -a n, diskinfo ok.

TTr, my problem is not related to lvm, extendfs, fsadm.

The problem is that I can't extend a FS online, though OnlineJFS is installed, if this FS resides on a raw device. I have to unmount the FS so that diskinfo shows the new size. After that I can "extendfs" before mounting, or mounting then "fsadm -b newsize".

OnlineJFS works well, the fact is that vmunix (diskinfo) doesn't return new sizes as long as the corresponding resource is in use. OnlineJFS has no sense if I have to unmount a FS to get the new size :-(

I can't believe it. Even under Windows, extending a LUN size works : new space is accessible at once after a disk scan ! Of course extending the FS is an other story.

Any idea ? Patch, kernel parameters, unknown command, ... ? Asking HP for modifying this behavior ;-) ?

Eric

Re: diskinfo doesn't return new size

Eric,

What happens if you try using the 'remount' option on a mount command:

mount -o remount /dev/dsk/c0t0d0 /myfs

Does it pick up the change in size then?

HTH

Duncan

I am an HPE Employee
Accept or Kudo

Re: diskinfo doesn't return new size

I should have indicated - you can run the remount command even with files open on the filesystem...

HTH

Duncan

I am an HPE Employee
Accept or Kudo
Eric SAUBIGNAC
Honored Contributor

Re: diskinfo doesn't return new size

Duncan,

I tried this option yesterday, but it was not the good way :-(

Eric
psreedhar
Frequent Advisor

Re: diskinfo doesn't return new size

I will check with the owner of the diskinfo command/SCSI services and let you the solution.
Eric SAUBIGNAC
Honored Contributor

Re: diskinfo doesn't return new size

There is no problem with the owner of "diskinfo". It works perfectly but the problem described before.

Eric