RE: USEOPTBLK effect on which drives?

["Bale, Dan" <D.Bale@xxxxxxxxxxxxx>]

Title: RE: USEOPTBLK effect on which drives?

Hi Sue!  Is H.A. your middle name?  <g>  Is the fishin' good in Silverlake?

Speed is not as much a factor as is the desire/goal/requirement to get the backup done on two tapes and not three.  I risk alienating the users who now have to put in a second tape first thing in the morning if I tell them that there's now a third tape to deal with every day.

Unless we reach a crisis point with our ability to do a complete backup, there will be no further hardware expenditures.  The best I may be able to do is to switch a 7208-222 from one of our other boxes with the 7208-012 on the capacity-challenged machine so that I can use 7GB cartridges as opposed to the 5GB's.

COMPACT(*YES) brings a syntax error at V3R7.  The only valid values are *DEV and *NO.  I use the default value of *DEV.  According to the V4R5 system handbook, it appears that the 7208-012 supports both the HDC (Hardware Data Compression) and the IDRC (Improved Data Recording Capability) compaction algorithm.  But HDC seems reliant on the IOP; do all of the IOP attachments for the 7208-012 support HDC?  (FWIW, it appears that we are using IOP #2621.)  Also the compaction algorithm appears to be dependent on the tape subsystem controller; is this "built-in" to the tape drive hardware?

*IF* our 7208-012 supports both HDC & IDRC, am I getting the maximum capacity by specifying DTACPR(*YES) & COMPACT(*DEV) ?

Dan Bale
IT - AS/400
Handleman Company
248-362-4400  Ext. 4952
D.Bale@Handleman.com
  Quiquid latine dictum sit altum viditur.
  (Whatever is said in Latin seems profound.)

-------------------------- Original Message --------------------------

-----Original Message-----
From:   S Baker [SMTP:gonfishinmn426@yahoo.com]
Sent:   Tuesday, August 14, 2001 7:50 AM
To:     midrange-l@midrange.com
Subject:        Re: USEOPTBLK effect on which drives?

Dan, USEOPTBLK works on the 7208-342 but not the other 7208 models.
 
DTACPR is really slow ... that's software compression of the data before sending to tape.
Better to use COMPACT(*YES) and have the tape hardware do the compression of the data.
 
Sue Baker

----- Original Message -----
From: Bale, Dan <mailto:D.Bale@handleman.com>
To: midrange-l@midrange.com <mailto:midrange-l@midrange.com>
Sent: Tuesday, August 14, 2001 12:57 AM
Subject: USEOPTBLK effect on which drives?

Can someone point me in the direction of the appropriate documentation that tells me whether USEOPTBLK(*yes) is effective on a 7208 model 012 tape drive on a V3R7 system?

 
Does USEOPTBLK(*YES) do any compression?  The help text doesn't really say anything except that it may offer a performance benefit.  I wondered about compression since USEOPTBLK(*YES) and DTACPR(*YES) cannot be used together.

 
If I'm tight on tape space and I've got plenty of time, would my better option be to use USEOPTBLK(*NO) and DTACPR(*YES)???

 
Thanks!
 
Dan Bale
Handleman Company