topic Re: Maximum cluster size for disks in Operating System - OpenVMS

Maximum cluster size for disks

Bart Zorn_1 — Tue, 22 Nov 2005 05:16:18 GMT

HELP INIT /CLUSTER states the following on both V7.3-2 and V8.2:

/CLUSTER_SIZE=number-of-blocks

Defines, for disk volumes, the minimum allocation unit in blocks.
The maximum size you can specify for a volume is 16382 blocks, or 1/50th the volume size, whichever is smaller.

The DCL Dictionary gives the same information.

Because I wanted to init a disk with a large cluster size (it needs to accomodate only a few very large files) and because I did not bother to read the help file upfront, I tried /CLUS=32768. INIT did not complain and afterwards, SHOW DEV/FULL displayed a cluster size of 32768.

Does anyone here know what the REAL maximum cluster size is?

Regards,

Bart Zorn

Re: Maximum cluster size for disks

Wim Van den Wyngaert — Tue, 22 Nov 2005 08:22:19 GMT

"The maximum cluster size for any volume is one hundredth the size of the volume".

help/mes/fac=init cluster

They must have forgotten to correct the doc.

Wim

Re: Maximum cluster size for disks

Bart Zorn_1 — Tue, 22 Nov 2005 08:53:58 GMT

Indeed, there it is!

That leaves me a cluster size that is surely big enough! (on a 600 GB disk).

Thanks,

Bart

Re: Maximum cluster size for disks

faris_3 — Tue, 22 Nov 2005 09:10:04 GMT

It seems that at least for V7.3-2, it is possible to have a cluster size of about
1/50 of the volume size :

1462 OR .VOLUME_SIZE / .CLUSTER LSS 50
1463 THEN ERR_EXIT (INIT$_CLUSTER);

Have not tested it though.