Bacula-users

Re: [Bacula-users] IBM TS-3100 too slow on bacula

2008-11-10 11:39:07
Subject: Re: [Bacula-users] IBM TS-3100 too slow on bacula
From: Alex Chekholko <chekh AT pcbi.upenn DOT edu>
To: jdinunci AT uc.edu DOT ve
Date: Mon, 10 Nov 2008 11:37:12 -0500
Hi,

I use the regular Linux tape driver (st), not the IBMTape driver, for my TS3310 
tape library.

Have you tried doing that?

Testing with dd and tar is a good idea, then move on to testing with btape.

Regards,
Alex

On Mon, 10 Nov 2008 09:35:52 -0430 (VET)
jdinunci AT uc.edu DOT ve wrote:

> Hello,
> 
> My Hardware:
>    Blade Center H, with 8 blades LS21 (1 AMD Opteron 2.4GHz, 6 GB ram)
>    The data comes from a SAN DS4700 (Fiber channel 4 Gb/s).
>    My tape library is a IBM TS3100 using tapes LTO-3 connected via fiber
>    channel.
> 
> My Software:
>   OS: Red Hat Enterprise Linux ES release 4.
>   I'm using bacula-2.4.3
> 
> 
> I've started with bacula 2.2.8 six months ago, making backups on disk. Then
> I made some test with the tape backup, following "Testing Your Tape Drive
> With Bacula", getting excellent BW. But then I upgraded to bacula 2.4.3 and
> somehow I ended misconfiguring my tape unit.
> 
> Now, backing up 15MB from the SAN to the tape takes almost 8min. My tape
> BW is just 33.0 KB/s. I tried backing up local data with the same BW.
> Then, I'd go back to the basic tests and discovered that the tape unit is
> working slow even without bacula. Example:
> 
>   # time dd if=/dev/sda of=/dev/IBMtape0 bs=1M count=100
> 
> takes 3min (572 KB/s). Changing bs=64K doesn't make too much difference.
> I get equivalent BW using tar. So, it seems to be a tape unit problem,
> but then I ran the IBM test program 'itdt' and got these numbers:
> 
> 
>    Block Size  Data Size    Elapsed    Data Rate
>       (KB)       (MB)       Time (s)    (MB/s)
>   +-----------+-----------+-----------+-----------+
>   | 512       | 41961     | 245.728   | 170.764   |
>   | 256       | 41961     | 242.377   | 173.125   |
>   | 128       | 41961     | 259.317   | 161.815   |
>   | 64        | 41961     | 293.884   | 142.783   |
>   | 32        | 41961     | 354.081   | 118.508   |
>   | 16        | 41961     | 484.687   | 86.5746   |
>   | 8         | 41961     | 746.556   | 56.2069   |
>   +-----------+-----------+-----------+-----------+
> 
> 
> So, the tape unit seems to be OK, after all.
> 
> My question is: is there a parameter in bacuala that allow me improve the
> BW of my tape unit?
> 
> My actual configuration looks like this:
> 
> bacula-sd.conf:
> ==============
>   [...]
> 
>   Device {
>     Name = TS3100
>     Archive Device = /dev/IBMtape0
>     Device Type = Tape
>     Media Type = TS3100
>     AutoChanger = yes
>     AlwaysOpen = yes
>     Removable Media = yes
>     Random Access = no
>     Requires Mount = no
>     Hardware End of Medium = no
>     Fast Forward Space File = no
>     BSF at EOM = yes
>     Two EOF = yes
>     #Offline on Unmount = yes
>     Drive Index = 0
>     Maximum Spool Size = 200100100100
>     Maximum Job Spool Size = 200100100100
>     Spool Directory = /reduc/var/bak/general/spool
>   }
> 
> Any ideas?
> 
> Thanks in advance.

-- 
Alex Chekholko  

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