topic Re: Contiguous space in a disk on VMS in Operating System - OpenVMS

Contiguous space in a disk on VMS

Sk Noorul Hassan — Wed, 11 Jan 2006 04:18:18 GMT

Hi all,

What are the ways to know the available contiguous space in a disk on VMS ?

Re: Contiguous space in a disk on VMS

John Abbott_2 — Wed, 11 Jan 2006 04:29:30 GMT

There are lots of possible reponses to this, but I guess an easy reply is to consider using a good tool from the VMS freeware collection, like this:

http://h71000.www7.hp.com/freeware/freeware70/dfu/

Re: Contiguous space in a disk on VMS

Marc Van den Broeck — Wed, 11 Jan 2006 04:30:18 GMT

Hi,

Use DEFRAG SHOW disc_name/VOL

Rgds
Marc

Re: Contiguous space in a disk on VMS

John Abbott_2 — Wed, 11 Jan 2006 04:33:54 GMT

For the freeware DFU too use

$ MCR DFU
DFU> report device
.
.
output here that gives lots of juicy info, look under the Free space stats for what you're after.
.
DFU> ^Z

Re: Contiguous space in a disk on VMS

Wim Van den Wyngaert — Wed, 11 Jan 2006 07:02:25 GMT

Without tools : make an fdl that created a file of size x with option contiguous.
If create/fdl fails then the space isn't available. Don't forget to delete the file afterwards.

Wim

Re: Contiguous space in a disk on VMS

Hein van den Heuvel — Wed, 11 Jan 2006 07:46:06 GMT

DFU is the preferred tool. Eveery system manager should know to use it.

Anyway, even with the tools, when running in a cluster you may want to instruct the system to allocate a large contiguous chunk before reporting. Why? Well each cluster node can (will) have a freeblock cache on the volume which may fragment the freespace for 'others'.
My favourite command for this: $COP/CONT/ALL=999999999 NL: tmp.tmp

Please help us understand why you think you need to know the largests contiguous chunk. Very few software cares about this anymore. Directories need to be contiguous. And I believe there is one database out there, not oracle, that requires it.

hth,
Hein.

Re: Contiguous space in a disk on VMS

Sk Noorul Hassan — Wed, 11 Jan 2006 08:08:01 GMT

I have no DFU loaded in the system. so, I have to go as suggested by WIM, or is there any other way ?

Re: Contiguous space in a disk on VMS

Wim Van den Wyngaert — Wed, 11 Jan 2006 08:25:14 GMT

The solution of Hein does the same.

You could write a procedure :

$ set noon
$cnt=1000000 ! or whatever
$b:
$ def/us sys$output nl:
$ def/us sys$error nl:
$ copy/cont/alloc='cnt' nl: xxx.lis
$ if $status
$ then
$ write sys$output "''cnt'"
$ del xxx.lis.*
$ else
$ cnt=cnt - 10000 ! or whatever
$ goto b
$ endif

Re: Contiguous space in a disk on VMS

Hein van den Heuvel — Wed, 11 Jan 2006 08:29:11 GMT

I suppose you could 'binary search' for the moment where a large contiguous file create starts to work. Not too hard, notably not with my $COPY techinque as you do not need a temp FDL file for that. Start with 2,000,000 blocks (less than 1TB), divide your way down and back up again.

And you could read [000000]bitmap.sys and count bits.

But WHY do you need to know? If it is for a file create, then just try that size.

If it is for a report, then for starters it is a pretty lame/ useless number and it may be good enough to report "Largest contig free space over 500MB", or over 100MB or whatever.

If it is for a serious report, then just knowing the largest chunk is probably not good enough anyway.

You could see whether the more official tool DFO provided teh data needed. It's reporting functions are free.

But anyway, you HAVE to get DFU on the box.

No self respecting OpenVMS syystem manager can live without. It's free, it's good, it's been around, it's highly available, and it has been written/maintained by a Dutch guy... it doesn't get any better!

Cheers,
Hein.

Re: Contiguous space in a disk on VMS

Wim Van den Wyngaert — Wed, 11 Jan 2006 08:53:28 GMT

But DFU is not standard. I want to challenge a newbe in this company to get a version downloaded from the internet on the VMS node. Security doesn't allow it.

IMHO : HP should have made the info available thru lexicals long time ago.

Wim

Re: Contiguous space in a disk on VMS

Ian Miller. — Wed, 11 Jan 2006 09:06:43 GMT

DFU was written by the Wizard of ODS2 and should be included with VMS. Certainly it should be installed on any VMS systems you have.

As to the original question - what are you trying to do? I wonder if you need to know this.

Re: Contiguous space in a disk on VMS

Sk Noorul Hassan — Wed, 11 Jan 2006 10:03:23 GMT

During my application startup after VMS boot, the start up getting terminated with an error "insufficient space, disk full' while trying to create section files on the system. My disk size is 2GB and free space available is almost 1.8 GB

Re: Contiguous space in a disk on VMS

Hein van den Heuvel — Wed, 11 Jan 2006 10:21:39 GMT

Hmmm... what is the EXACT message. I don't recognize yours directly:

FUL, device full (insufficient space for allocation)
VOLUME_FULL, volume is full (insufficient space for the request)
DEVICEFULL, device full; allocation failure
:

And how big are those section files going expected to be?

2GB drives (RZ26?) are not too big compared to physical memory and virtual memory these data.
You know that when you initialize a disk, the defautl place for INDEXF.SYS is in the middle right? So max contig would be 1GB, unless one uses INIT/INDEX=...

Are you sure it is a problem with the data disk? Could it be the audit system running out of system disk of something like that?

Hein.

Re: Contiguous space in a disk on VMS

Ian Miller. — Wed, 11 Jan 2006 10:22:24 GMT

have you used one of the methods described to determine the largest contiguous free space?

Re: Contiguous space in a disk on VMS

Ian Miller. — Wed, 11 Jan 2006 10:23:18 GMT

Do you know why the application wishes to create a contiguous file?

Re: Contiguous space in a disk on VMS

John Abbott_2 — Wed, 11 Jan 2006 10:23:20 GMT

Sounds more like you should just backup and restore (ie. defrag the volume).. assuming you have the hardware and time.

Also, as per Marc's suggestion with DFO, I thought this HP product was free to use in report mode ?

Failing that, try the freebie report image tool from HP...

http://h71000.www7.hp.com/openvms/storage/dfopage.html

Regards
John.

Re: Contiguous space in a disk on VMS

Sk Noorul Hassan — Thu, 12 Jan 2006 04:03:55 GMT

The exact error is, device full; allocation failure

Can it be solved by taking Image backup to a different disk and restore it back ?

Re: Contiguous space in a disk on VMS

Wim Van den Wyngaert — Thu, 12 Jan 2006 04:25:14 GMT

I would do "anal/disk/rep" for the disk first. Maybe the free space counters are not correct. Maybe you should do a cleanup.

Wim

Re: Contiguous space in a disk on VMS

Sk Noorul Hassan — Thu, 12 Jan 2006 05:42:30 GMT

I did clean up and ana/disk/repair for the disk, still the problem exist. I am unable to create a file of space 10000 blocks also.

Re: Contiguous space in a disk on VMS

Wim Van den Wyngaert — Thu, 12 Jan 2006 06:01:40 GMT

Then you need to backup and restore, as said.
Or buy defrag.

Wim