topic Re: Backup Size in Operating System - OpenVMS

Backup Size

Sentosa — Wed, 13 Jun 2007 04:07:40 GMT

Dear All,

I want to perform backup from disk to saveset.
-Backup/image/log/block=65535 DISKA: DISKB:[000000]DISKA_BACKUP.SAV/sav

How many space i need for the saveset if DISKA has around 20GB data?

Thanks,
Sentosa

Re: Backup Size

Wim Van den Wyngaert — Wed, 13 Jun 2007 04:20:09 GMT

About 22 GB ? (if size was received with dir/siz=used). 2 GB group overhead.

Check backup /group=0 to reduce the size. Use /ign=int to get all files even when they are open.

Wim

Re: Backup Size

Heinz W Genhart — Wed, 13 Jun 2007 04:23:14 GMT

Hi Sentosa

I do backup of my disks at home over a VPN to another OpenVMS machine located at my office 10 km away on a daily base.

Here some examples about saveset sizes:

Dir/grand disk: Saveset size
2.89 GB 2.52 GB 87.2%
541.19 MB 476.6 MB 88.1%
600.23 MB 505.59 MB 84.2%

Regards

Geni

Re: Backup Size

Heinz W Genhart — Wed, 13 Jun 2007 04:26:01 GMT

Hi Sentosa

I forgott to add the backup command used

I do:

BACKUP/IMAGE/RECORD/IGNORE=(INTERLOCK) Disk: remote_location::disk:[dir]saveset.bck/sav

Regards

Geni

Re: Backup Size

labadie_1 — Wed, 13 Jun 2007 04:29:11 GMT

Wim said
Use /ign=int

or /allow=corruption, which is the same

:-)

Re: Backup Size

Wim Van den Wyngaert — Wed, 13 Jun 2007 04:46:48 GMT

Labadie,

It is essential for the size test to have ALL files.

Geni,

siz=used ? I tested a small disk over here and got 10% bigger save set size.

Wim

Re: Backup Size

Wim Van den Wyngaert — Wed, 13 Jun 2007 04:49:05 GMT

I had 5837 files, size 779760 and the saveset was 857241. All with real files (not marked nobackup).

Wim

Re: Backup Size

labadie_1 — Wed, 13 Jun 2007 04:54:14 GMT

Wim

just joking

Re: Backup Size

Heinz W Genhart — Wed, 13 Jun 2007 05:07:37 GMT

Hi Sentosa & Wim

It was the allocated size, sorry.

Here some examples about saveset sizes:

Dir/grand disk: Saveset size
(size used)
2.24 GB 2.52 GB 112.5%
427.33 MB 476.6 MB 111.53%
468.23 MB 505.59 MB 107.98%

Regards

Geni

Re: Backup Size

Karl Rohwedder — Wed, 13 Jun 2007 05:19:09 GMT

Since V8.3 you may add a /DATA=COMPRESS, which reduces the saveset size considerably (we have reductions up to 80%).

regards Kalle

Re: Backup Size

Wim Van den Wyngaert — Wed, 13 Jun 2007 05:53:22 GMT

But still add /group=0 because the default is stuppid for disks (and also for most tapes).

Wim

Re: Backup Size

Dave Gudewicz — Wed, 13 Jun 2007 09:43:45 GMT

You might want to check on using a blocksize=65535 to disk. Isn't the maximum backup blocksize to disk=32768 ?

Dave...

Re: Backup Size

Wim Van den Wyngaert — Wed, 13 Jun 2007 10:01:16 GMT

"Backup may adjust this value according to the constraints of the backup format" (help)

Re: Backup Size

Dean McGorrill — Wed, 13 Jun 2007 12:14:12 GMT

In the old days, if it was user disk we added /igno=nobackup to. This is because we
were told we must protect the users from
themselves in case they set file/nobackup.
(Eh a philosophy, it stuck with me on non system disks)

Re: Backup Size

Steven Schweda — Wed, 13 Jun 2007 14:52:40 GMT

> You might want to check on using a
> blocksize=65535 to disk. Isn't the maximum
> backup blocksize to disk=32768 ?

HELP BACKUP /BLOCK_SIZE

" [...] the default for disk is 32,256 bytes."

And that is the maximum, because the maximum
record size on disk is 32767, and 32256 is
the biggest multiple of 512 (one disk block)
which is less than 32768.

Re: Backup Size

Dave Gudewicz — Thu, 14 Jun 2007 10:49:59 GMT

>And that is the maximum, because the maximum
>record size on disk is 32767, and 32256 is
>the biggest multiple of 512 (one disk block)
>which is less than 32768.

Thanks for the clarification. And I think that the backup documentation (not help) needs some attention in that it states in the System Manager's Manual Vol 1 on page 434 in table 11-4:

"Note: To be able to copy save sets from tape to disk, use a maximum block size of 32,768."

Dave...