add volume groups and file systems while system up?

[Fred Martin_1]

I'm going to add a couple of disks to my system. Once the hardware is in, I'll bring them up and verify that addresses are good and that ioscan can see the disks.

At that point, can I let users back on and finish configuration while the system is up?

Each disk will be alone in a new volume group, and each will have one file system. No striping, nothing fancy.

I'm hoping that the downtime for users will be a few minutes for hardware, and that's it.

Possible?

[melvyn burnard · Accepted solution]

most definitely, provided the actual installation of hte hardware goes well, and htere is nothing to change in hte kernel, such as maxvgs

[A. Clay Stephenson]

Absolutely; in fact, if your disks are hot-plug then you don't even need to bother with a shutdown. In that case, all you have to do in pop the disks in, do an ioscan -fn (no -k - we want to rescan the hardware), an insf, and you are now ready to do your pvcreates.

[James R. Ferguson]

Hi Fred:

Yes, you can let your users onto the system and continue to create new volume groups, logical volume and filesystems. In fact, one of the reasons for licensing OnlineJFS is to allow dynamic resizing of filesystems while "normal" operations continue.

Regards!

...JRF...

[Steven E. Protter]

Yes.

ioscan

ioscan -fnC disk

make sure the disks are claimed.

pvcreate /dev/rdsk/c#t#d0

replace the # with real numbers.

mkdir /dev/vg##
mknod
vgcreate

vgextend /dev/vg## /dev/dsk/c#t#d0

SEP

[Fred Martin_1]

Thanks folks. I assume I can do all this through SAM. Let me know if not.

The disks are HP A5239A, they're to go in an enclosure A3312A.

I was told the disks are hot-swappable but not hot-pluggable, i.e. I'll install the disk on downtime Sunday, then configure the file systems using SAM on Monday when I'm actually being paid :)

[James R. Ferguson]

Hi Fred:

If you are not comfortable with command-line LVM, then by all means, usse SAM to configure!

Regards!

...JRF...

[A. Clay Stephenson]

You definitely do not need to powerdown. There is no rigorous definition for "hot-plugable" and "hot-swappable". They are typically used interchangably. In your context, hot-plug is taken to mean pop old out, pop new in, and walk away, ala AutoRAID's. Hot-swap means pop out old drive, pop in new drive, BUT further user intervention is required to restore the drive to useful service.

You disk modules can be safely plugged in, one at a time. Each will trigger a reset of that SCSI bus but that is considered a normal event for SCSI and will be handled gracefully by the system. As soon as all the drives on the bus become ready again (typically a few seconds), you can insert the next drive.

If things didn't work like this ServiceGuard Clusters would be of little use because those disks (even the ones exactly like yours) are replaced routinely 'on the fly'. Believe it or not, I have not shutdown to replace a failed disk in over five years --- and I replace one or two a week.

[Fred Martin_1]

So you're saying I could walk over there right now and slide one of those disks in place? Remember these are new to the system, not replacing existing drives.

[Fred Martin_1]

And - I just realized - although the slots already are assigned addresses that are not being used - the two new disks are on 'column B' of the enclosure which is not cabled. 'column A' is terminated. I have to add a cable from column A to column B, and move the terminator.

I think I'd feel better if the system were down for that.

[PIYUSH D. PATEL]

Whenever you are changing the "terminators" and swapping the cables you need to bring the system down. Regarding changing the didsk, you need to go through the user manual of your disk enclosure for more information.

HTH,
Piyush

[Steven E. Protter]

Fred, I think you are right.

It is surprising that any of the disk slots are not cabled though. On every system I have ever looked at, plus a few Jamaica boxes(also hot swap) all drive slots are cabled.

I never mess with cables on hot systems.

But the principle is clear. I was scared the first time, but all you have to do is slide that disk in, and run ioscan, then its available for configuration as noted in my earlier post.

Soon I think you'll no longer be a hot-swap virgin.

Regards,

SEP

[Fred Martin_1]

The cable thing was my doing. When I originally installed the enclosure, since there were no disks in the second column, I didn't cable the second column (this enclosure is set up so that the two columns can be indendently cabled to two different controllers, or chained together on one).

Ok so I'll bring it down, cable it, and pop the disks in. Only take a few minutes.

Have a great weekend folks.

[Caesar_3]

Hello!

After you will bring it up, your users
could continue to work and you could add
the disks to the system.
You can use SAM or the command line as you like.

Good luck.

Caesar