Expanding/Extending EVA Volume on OpenVMS

[Karen Lee_3]

What is involved in extending an EVA drive with Alpha system running OpenVMS 7.3-2? Is it a simple matter of dismounting and remounting the drives? is a reboot required?

[Volker Halle · Accepted solution]

Karen,

after the appropriate preparation, an OpenVMS volume can be extended dynamically (it's called DVE = Dynamic Volume Expansion).

First check the volume expansion limit with

$ SHOW DEV/FUL DGAx:
...
Logical Volume Size nnn Expansion Size Limit nnn

If your desired new volume size (on EVA) is less than the Expansion Size Limit, you can simply extend the disk online with:

$ SET VOLUME/SIZE DGAx:

If the current Expansion Size Limit is too small, you need to increase it. This can ONLY be done while the disk is mounted privately:

$ SET VOLUME/LIMIT DGAx:

You can then re-mount the disk system-wide and actually extend it with SET VOLUME/SIZE DGAx:

Caveats:

- If you need to do this to the system disk, use the V8.2 OpenVMS operating system CD. V7.3-2 has a bug and won't work.

- you need sufficient contig space to increase the Expansion Size limit (new BITMAP.SYS needs to fit).

Volker.

[Karen Lee_3]

Ok, here is the settings for the disk i want to expand

Logical Volume Size 419430400 Expansion Size Limit 478384128

Since my expansion size is larger, i can just do a set size up to the expansion size limit? correct?

[Volker Halle]

Karen,

yes - if 478 million blocks is the size you want this disk to be expanded to from the OpenVMS point of view. You may loose some blocks due to rounding.

A SET VOLUME/LIMIT would set the Volume Expansion Size to 1 TB by default.

For more details, see HELP SET VOLUME/LIMT and /SIZE or read the documentation.

Volker.

[Jan van den Ende]

Karen,

Volker wrote

A SET VOLUME/LIMIT would set the Volume Expansion Size to 1 TB by default.


minor note: this is true only if the disk cluster size is at least 8.
For smaller cluster sizes it is 1/8 Tb * (clustersize).
This has to do with the maximum number of adressable individual clusters.

hth

Proost.

Have one on me.

jpe

[Karen Lee_3]

i need to re-open this issue - because i'm actually trying it for the first time.

I dismounted the disk - then did

$mount $1$dga5: studylg7

the disk was 200gb - i want to expand to 250gb. so i did

$set volume/limit=500000000

dismounted it and remounted it using my regular mount/sys command.

it shows the volume limit reset from 419430400 to 598155264 but it doesn't i doesn't show up as having any more free space

karen

[Robert Gezelter]

Karen,

The dynamic volume expansion fixes the structures on the disk. The size of the actual disk (or EVA volume) needs to be increased.

The example (on the VMS side) of what I believe you are attempting is covered in my presentation from th 2005 HP Technology Forum, "Migrating OpenVMS Storage Environments without Interruption or Disruption" (notes at http://www.rlgsc.com/hptechologyforum/2005/1146.html ).

The EVA end will depend on which EVA and how things are configured.

- Bob Gezelter, http://www.rlgsc.com

[Volker Halle]

Karen,

$ SET VOL/LIMIT extends the BITMAP.SYS file, which controls the no. of blocks (clusters) allocatable on that volume.

Once you have made the disk bigger (on the EVA storage controller), you can then issue $ SET VOL/SIZE - while the voule is mounted system/cluster-wide - to dynamically increase the size of the disk.

Volker.

[Karen Lee_3]

I must be doing something wrong

my disk shows

Logical Volume Size 419430400 Expansion Size Limit 598155264

When I type

$set volume/size 524288000 $1$dga5:

it accepts the command without an error - but the disk still shows 97%full.

[Volker Halle]

Karen,

what does SHOW DEV/FULL $1$DGA5 show as Total Blocks ?

Volker.

[Karen Lee_3]

no change in total blocks from original 200gb size

Total blocks 419430400 Sectors per track 128
Total cylinders 25600 Tracks per cylinder 128
Logical Volume Size 419430400 Expansion Size Limit 598155264
Allocation class 1

Volume label "STUDY7" Relative volume number 0
Cluster size 171 Transaction count 1
Free blocks 10874574 Maximum files allowed 1219274

[Volker Halle]

Karen,

Total Blocks is what OpenVMS currently believes about the physical size of the disk. This size is updated during mount-verifications (with the IO$_PACKACK QIO).

Assuming you already did increase the size of this disk on the EVA to 250 GB, consider to force a mount-verification on that disk.

The $ SET DEV/SWITCH/PATH=other-path $1$DGA5: could be used, but you could also temporarily disconnect the Fibre Cable for the current path ;-)

Volker.

[Karen Lee_3]

no one is using the disk at the moment - if I use the command

"$ SET DEV/SWITCH/PATH=other-path $1$DGA5: "

i don't have to specifiy what 'other-path' is?

[Volker Halle]

Karen,

use SHOW DEV/FULL $1$DGA5: to see all pathes to that disk, then explicitly specify a non-current path. You can later switch back to the current path.

If noone is using the disk, you could also dismount and mount it, but the goal of this experiment is to increase the disk while it's mounted system-wide...

Volker.

[Karen Lee_3]

i did a dismount then a reload of the disk and no change - i think my EVA guy is pulling my leg about increasing it to 250gb - i'm going to check with him when he get's in

[Karen Lee_3]

b.t.y - is 524,288,000 the correct block size for 250 gb size?

[Volker Halle]

Karen,

... should be about right. Depends whether 1k is 1000 or 1024. You shouldn't need to care about that.

Volker.

[Karen Lee_3]

so if he really increased the correct volume, then

$set volume/size=524288000 should at least change the 'total blocks' size - correct?

[Volker Halle]

Karen,

if the disk size on the EVA has been increased AND you have forced a mount-verification on that disk or remounted it, THEN Total Blocks should show the increased PHYSICAL DISK SIZE.

A $ SET VOL/SIZE[=xxx] $1$DGA5: would then increase the Logical Volume Size (=size of disk useable by the file system) appropriately. xxx must be larger than the current Logical Volume Size and less-or-equal to Total Blocks. The default for xxx is the Total Blocks value. The maximum possible Logical Volume Size is also limited by the Expansion Limit.

Volker.

[Karen Lee_3]

Since my "total blocks" is not changing from the original 419430400 - and my new size must be less-or-equal to total blocks - i'm assuming that's why nothing will adjust.

my EVA guy is in around 9:00 cst - will hound him then to re-check his settings. Yesterday he was absolutely adament about his settings.

[Volker Halle]

Karen,

yes, your first goal is to make Total Blocks of your disk bigger than it's now.

OpenVMS won't allow you to increase the Logical Volume Size above the Total Blocks of the disk - where should it put those other blocks ???

Volker.

[Robert Gezelter]

To the moderators,

An errata occurred in earlier posting in this thread.

The correct URL for my session notes is: http://www.rlgsc.com/hptechnologyforum/2005/1146.html

While I do not like to correct the historical record, perhaps a correction of this typographical error would be appropriate to ease access to the referenced material.

- Bob Gezelter, http://www.rlgsc.com