News Group Posts

tape blocksize compression

Newsgroups: comp.unix.sco.misc
From: "D. Thomas Podnar" <tom@microlite.com>
Subject: Re: Tape Drive Problems
Date: Fri, 31 Dec 1999 21:50:17 GMT
Message-ID: <199912311650.aa02571@mlitedom.microlite.com> 

Jerad Stoops <jms@sofnet.com> Wrote:

: I have two SCO Openserver 5.0.5 systems. One has an Aiwa TD-8001NS 4GB/8GB
: travan scsi tape drive, the other system has an HP Colorado 4GB/8GB travan
: ide tape drive. All of the backups that I make on the Aiwa can't be read on
: the HP.  I've tried tar, pax, cpio from the command line and the sco shell
: utilities and even the gui backup manager but none can be read. The backup
: either doesn't read at all or it gives an End of medium message asking for
: the next tape. The command that SCO recommends is:
: find /u -print | cpio -ocvB -O/dev/rct0  ... but even it didn't work.
: Supposedly the problem is related to the end of file mark placed on the tape
: by the tape drive.
: 
: If anybody has any info. I would greatly appreciate it.

OK, this is from memory but:

The Aiwa drive is Imation NS certified, meaning that it has read-after-write
heads and uses a standardized hardware compression.

The HP has NO hardware compression and the 8GB part means "if you are
using a backup program that averages 50% compression".

To make them speak, you have to "dumb down" the Aiwa by turning off
hardware compression.

Under OpenServer 5.0.x

  tape -a 0 setcomp /dev/xStp0
 
or with BackupEDGE

  edge.tape -arg 0 -C /dev/xStp0

To verify this, one would issue:

  tape getcomp /dev/xStp0
or
  edge.tape -a /dev/xStp0


One additional possibility that may cause problems:

The tape drives may power up in different hardware block modes:

  tape getblk /dev/xStp0
or
  edge.tape -g /dev/xStp0

For instance, one may be set at 512 and one may be set at 0 (variable). 

To make them identical at 0, one would issue:

  tape -a 0 setblk /dev/xStp0
or
  edge.tape -arg 0 -B /dev/xStp0

For identical at 512 byte blocks, it would be:

  tape -a 512 setblk /dev/xStp0
or
  edge.tape -arg 512 -B /dev/xStp0

Best regards, and Happy New Year to all!


Tom
---
  D. Thomas Podnar - President          tom@microlite.com  Email
  Microlite Corporation                 724-375-6711       Voice
  2315 Mill Street                      724-375-6908       Fax
  Aliquippa PA 15001-2228               888-257-3343       Toll Free Sales
+--------------------------------------------------------------------------+
|                      The Crash Recovery Company(sm)                      |
+--------------------------------------------------------------------------+
| Makers of Microlite BackupEDGE  - Data Archiving Software For Unix/Linux |
|       and Microlite RecoverEDGE - The ONLY Crash Recovery Software       |
|                                   Available for Linux, UnixWare 7.1,     |
|                                   SCO OpenServer 5.0.x and SCO Unix.     |
| http://www.microlite.com                         ftp://ftp.microlite.com |
+--------------------------------------------------------------------------+

Comments?

Jump to Comments

Many of the products and books I review are things I purchased for my own use. Some were given to me specifically for the purpose of reviewing them. I resell or can earn commissions from the sale of some of these items. Links within these pages may be affiliate links that pay me for referring you to them. That's mostly insignificant amounts of money; whenever it is not I have made my relationship plain. I also may own stock in companies mentioned here. If you have any question, please do feel free to contact me.

Specific links that take you to pages that allow you to purchase the item I reviewed are very likely to pay me a commission. Many of the books I review were given to me by the publishers specifically for the purpose of writing a review. These gifts and referral fees do not affect my opinions; I often give bad reviews anyway.

We use Google third-party advertising companies to serve ads when you visit our website. These companies may use information (not including your name, address, email address, or telephone number) about your visits to this and other websites in order to provide advertisements about goods and services of interest to you. If you would like more information about this practice and to know your choices about not having this information used by these companies, click here.