News Group Posts

microlite backupEDGE tape compression

Newsgroups: comp.unix.sco.misc
From: "D. Thomas Podnar" <tom@microlite.com>
Subject: Re: BackupEdge 1.01.08
Date: Wed, 29 Nov 2000 22:55:30 GMT
Message-ID: <200011292255.RAA06360@mlite.microlite.com> 

        I have been using BackupEDGE version 1.01.06, which seems
        much more user friendly than newer version 1.01.08
        
        I have installed the newer edge version 1.01.08 on SCO 5.06
        and I am having alot of trouble getting 1.01.08 to read/restore 
        tapes made using 1.01.06 on SCO 5.05. (the tape will read/restore
        on a machine using edge 1.01.06 on SCO 5.05)
        
        Has anyone else found this problem ? 
        
        Peri

Have you discussed your issues with our support staff?

Email support is FREE, FOREVER to registered BackupEDGE users.

The /bin/edge binary that does the reading and writing is essentially
the same in 01.01.06, 01.01.07 and 01.01.08. Your compatibility problem
is related to other factors, which we'll examine below.

As a general rule, 01.01.08 is a lot smarter about dealing with hardware
devices than 01.01.06. Since it does more it is a little bit more
complicated. Here are some rules of thumb...

1a) BackupEDGE 01.01.06, by default, used the power up hardware block
    size and compression defaults of a tape drive.

1b) BackupEDGE 01.01.08 can specifically set both of these items, although
    it tries to be smart about using defaults.

1c) If you write at one hardware block size, you cannot read at a different
    one, no matter which program you use. This includes tar, CPIO, you
    name it.

1d) Different brands of tape drives have different power up default modes.
    For instance, H-P DDS drives usually power up in variable block mode
    (block size 0), while Seagate and Sony tape drives usually power up
    with a hardware block size of 512. If you want to write on one, then
    read on the other, one has to be changed via a software switch.


2)  The same is SOMETIMES true of hardware compression, but usually only
    with older tape drives where there were some models that support
    hardware compression, and some that don't, but use the same media.
    In these instances, compresion OFF is the least common denominator.


For improved compatibility:

a) After a hardware power up, issue the following command to the OLD system.

     /usr/lib/edge/bin/edge.tape -g /dev/rStp0

   Record the current block size setting.

b) After a hardware power up, issue the following command to the NEW system.

     /usr/lib/edge/bin/edge.tape -g /dev/rStp0

   Record the current block size setting.

c) If they are different, change the new system by setting the hardware
   block size in the resource manager
     (edgemenu -> Admin -> Define Resources)
   to be the same as the old system.

   A value of -1 means to use the power up value of the drive. BackupEDGE
   will not fiddle with hardware block size if -1 is set.

d) If they are the same, check the compression with:

     /usr/lib/edge/bin/edge.tape -a /dev/rStp0

If none of the above is helpful, try our support department at
support@microlite.com

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
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