[KLUG Members] why is my tape drive so slow???

[Mike Williams]

>
>
>Subject: Re: [KLUG Members] why is my tape drive so slow???
>From: Adam Williams <adam@morrison-ind.com>
>To: members@kalamazoolinux.org
>Date: Thu, 20 Nov 2003 14:28:16 -0500
>Reply-To: members@kalamazoolinux.org
>
>  
>
>>> standbys like dump and tar.  The problem is neither of these seem to be 
>>> able to use the tape efficiently.  It keeps backing up, 
>>    
>>
>
>It is "shoe-shining".
>
>  
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>>> I assume because 
>>> the system isn't feeding it data fast enough.  
>>    
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>
>Most likely.
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>  
>
>>> Here's the hardware 
>>> details:  Pentium 2 350, 192 Megs memory.  Drive system is an LVM mirror 
>>> of fairly new 60 gig IDE hard drives.  tape is a Seagate DDS-3 SCSI 
>>> (although I've had the same problem with an HP Colorado TR-4) controlled 
>>> by an Adaptec 2940UW.  Redhat Linux 8.0, standard Kernel.  Since I don't 
>>> run XWindows, shouldn't this machine be more than capable of keeping up 
>>> with the tape drive?
>>    
>>
>
>If you do a "mt -f /dev/st0 status" what does it say?  Are you passing
>tar any blocking factors?
>

I was wondering if there was a way to force larger buffers or something, 
but no.  Don't know how to pass tar a blocking factor.  In fact, I'm not 
even sure what it means! ;-\  Anyway, here's the output from mt -f 
/dev/st0 status:

[root@moore root]# mt -f /dev/st0 status
SCSI 2 tape drive:
File number=0, block number=0, partition=0.
Tape block size 0 bytes. Density code 0x25 (DDS-3).
Soft error count since last status=0
General status bits on (41010000):
 BOT ONLINE IM_REP_EN

How would bus errors show themselves?  I don't think that's the problem, 
though, because the few times I've been able to explain to Bacula what 
want it to do it runs the tape without "shoe-shining".  Shoe-shining 
being my word of the day...