Performance in Linux DLT1 VS80 tape drives

Roddy McColl roddy at physicsgate.swmed.edu
Thu Apr 11 11:04:01 CDT 2002


Hope this isn't too naive, but its a two part question.

1) Will the grub.conf change (st=128) affect the working of the dd command?
2) This doc below describes using tar for backup. Does anyone out there use
   dd? I don't understand why tar would be preferable to dd since
   there is no interactive restore capability with tar.

TIA

-roddy

       -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
         Roddy McColl PhD      roddy at mri.swmed.edu
	 UT Southwestern            (214) 648-2910
	 http://www-mri.swmed.edu/homes/roddy.html
       -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-


> 
> This is for info purposes for customers with the DLT1 or VS80 and
> performance in linux.
> 
> -----Original Message-----
> From: Bill Spicer [mailto:bspicer at ccmsi.com]
> Sent: Wednesday, April 10, 2002 3:14 PM
> To: 'Steve_Boley at Dell.com'
> Subject: RE: Partitioning Array
> 
> 
> Wow, your right. I can't believe the difference. It went from a 9 hour
> backup to a 2 hour backup.
> 
> thanks.
> 
> bill
> 
> -----Original Message-----
> From: Steve_Boley at Dell.com [mailto:Steve_Boley at Dell.com]
> Sent: Wednesday, April 10, 2002 8:18 AM
> To: bspicer at ccmsi.com
> Subject: RE: Partitioning Array
> 
> 
> No way to verify, it's on by default and apparently there is not a jumper to
> enable or disable.  The blocksize will give a huge increase in performance.
> We see this not only in linux but also in backup exec and windows it sets
> the default blocksize to 1k and is incredibly slow.  You should see the
> performance drop to the 4 hour range or less after setting the blocksize.
> You should just pass it at the commandline with tar and see what your speed
> difference is and then pass at the kernel after verifying that this is your
> issue.
> steve
> 
> -----Original Message-----
> From: Bill Spicer [mailto:bspicer at ccmsi.com]
> Sent: Wednesday, April 10, 2002 8:12 AM
> To: 'Steve_Boley at Dell.com'
> Subject: RE: Partitioning Array
> 
> 
> Thanks. I may try this.  Our AIX Server (this poweredge is replacing this
> server) takes only 5 hours to backup our data. This PowerEdge takes 9 hours.
> Doesn't seem right as the old AIX server has an older 15/30 dlt and it's a
> two 200 Mhz processor server where as the Dell PowerEdge has a newer 40/80
> DLT and it's dual 1.2 Mhz.
> Any way to verify compression is on?
> 
> -----Original Message-----
> From: Steve_Boley at Dell.com [mailto:Steve_Boley at Dell.com]
> Sent: Tuesday, April 09, 2002 1:47 PM
> To: bspicer at ccmsi.com
> Subject: RE: Partitioning Array
> 
> 
> See the correction below.
> Steve
> 
> -----Original Message-----
> From: Bill Spicer [mailto:bspicer at ccmsi.com]
> Sent: Tuesday, April 09, 2002 1:42 PM
> To: 'Steve_Boley at Dell.com'
> Subject: RE: Partitioning Array
> 
> 
> Where do I put it. Here is my grub.conf
> 
> #boot=/dev/sda3                                       
> default=0                                             
> timeout=10                                            
> splashimage=(hd0,2)/grub/splash.xpm.gz                
> title Red Hat Linux (2.4.7-10smp)                     
>         root (hd0,2)                                  
>         kernel /vmlinuz-2.4.7-10smp ro root=/dev/sda8 st=128
>         initrd /initrd-2.4.7-10smp.img                
> 
> 
> Bill
> 
> -----Original Message-----
> From: Steve_Boley at Dell.com [mailto:Steve_Boley at Dell.com]
> Sent: Tuesday, April 09, 2002 1:26 PM
> To: bspicer at ccmsi.com
> Subject: RE: Partitioning Array
> 
> 
> Hardware compression is on by default.  Here is something you can add to
> either your grub.conf kernel parameters or you can pass it during tar to set
> the blocksize and will change your backup speed phenomenally.
> 
> st=128 for the kernel parameter or tar -cvf /dev/st0 -b 128 /?????
> 
> This will make a huge difference in your performance.  Here is a url to a
> pdf document at Benchmark's website explaining all the options.
> 
> http://www.benchmarktape.com/uploads/support/DLT1_Linux.pdf
> 
> Steve
> 
> -----Original Message-----
> From: Bill Spicer [mailto:bspicer at ccmsi.com]
> Sent: Tuesday, April 09, 2002 12:42 PM
> To: 'Steve_Boley at Dell.com'
> Subject: RE: Partitioning Array
> 
> I do have another question though. I'm trying to figure out how to turn on
> tape drive hardware compression so when I tar off data it's quicker.   I
> don't want to use tar's compression. There should be a setting to set
> hardware compression.  Any ideas.  
> 
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