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Re: Saveset blocksize on tape to allow COPY to disk

 
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Art Wiens
Respected Contributor

Saveset blocksize on tape to allow COPY to disk

I know that I've read (and experienced) that a saveset on tape can only have a maximum blocksize if at some point you want to mount the tape files-11 and copy the saveset to disk. I thought this value was /block=32768. I've searched for about an hour now but for the life of me can't find that reference.

I have such a saveset from a VAX v6.2 system disk that I want to get off tape and onto another disk on my test v7.3-2 Alpha. I want to do this because I will need to restore it into an LD disk a few times and don't want to wait on tape restore each time.

The disk was originally backed up on a TZ88 with:

$ backup -
/image -
/ignore=(interlock,nobackup) -
$40$DIA5: -
MKA200:060225.bck -
/save /noinitialize -
/label=060225 -
/media_format=compaction -
/block=32768

The error I get is:

$ copy mkc300:[]060225.bck dkb400:[vax_disks]
%COPY-E-OPENIN, error opening MKC300:[]060225.BCK;1 as input
-RMS-F-IRC, illegal record encountered; VBN or record number = 0

I'm fairly certain this is the message when the blocksize on tape is too big.

What's the "magic" number?

Thanks in advance,
Art
26 REPLIES 26
Art Wiens
Respected Contributor

Re: Saveset blocksize on tape to allow COPY to disk

Man they should make this thing Courier font!!

For clarity ...

mkc300:[ no spaces in here ]060225.bck

It's not a "box",
Art
Bill Hall
Honored Contributor

Re: Saveset blocksize on tape to allow COPY to disk

Art,

The "magic" number is 32256.

Bill
Bill Hall
Bill Hall
Honored Contributor

Re: Saveset blocksize on tape to allow COPY to disk

Art,

Backup writes a saveset to disk with a record format of "Fixed length 32256 byte records". The "magic" number is 32256.

Bill
Bill Hall
Bill Hall
Honored Contributor
Solution

Re: Saveset blocksize on tape to allow COPY to disk

Art,

Backup writes a saveset to disk with a record format of "Fixed length 32256 byte records". The "magic" number is 32256.

Bill
Bill Hall
Jim_McKinney
Honored Contributor

Re: Saveset blocksize on tape to allow COPY to disk

32767 is the max - and I think that BACKUP rounds up to then next increment of 512 so you should probably specify 32000 or 32256 if you want to be able to copy to disk.
Uwe Zessin
Honored Contributor

Re: Saveset blocksize on tape to allow COPY to disk

- /block=32768

RMS uses a signed word (16-bit value) on disk to maintain the record length, because -1 (and -2 ?) are used for special meanings. 32768(10) = 8000(16) gives an error as it does not fit into a signed 16-bit value (-32768..0..32767).


- mkc300:[ no spaces in here ]060225.bck

the "[]" is not necessary, unless your "SET DEFAULT" is on a search list. In that case, you will end up with several copies on disk, because RMS takes the directory default from the search list.

Many people are aware of this by now - a typical call from somebody new to VMS is when he does a:
$ directory tape:
while logged in to SYSTEM. The workaround is easy:
$ directory tape:[] ! ;-)
.
Uwe Zessin
Honored Contributor

Re: Saveset blocksize on tape to allow COPY to disk

Ah, and why 32256?

Easy: it's 32768 - 512
.
Phillip Thayer
Esteemed Contributor

Re: Saveset blocksize on tape to allow COPY to disk

If you just want to move the .BCK file to disk then why don't you do:

BACKUP MKC300:[]060225.BCK dkb400:[vax_disks]060225.BCK/LOG

This might work. I'm not sure.

Phil
Once it's in production it's all bugs after that.
Art Wiens
Respected Contributor

Re: Saveset blocksize on tape to allow COPY to disk


%BACKUP-F-ONEF11DEV, both input and output must not be save sets

Art