Amanda-Users

Re: Speed up 400GB backup?

2004-07-21 15:24:31
Subject: Re: Speed up 400GB backup?
From: Kris Vassallo <kris AT linuxcertified DOT com>
To: Joshua Baker-LePain <jlb17 AT duke DOT edu>
Date: Wed, 21 Jul 2004 12:17:53 -0700
On Tue, 2004-07-20 at 17:28, Joshua Baker-LePain wrote:
On Wed, 21 Jul 2004 at 12:00am, Stefan G. Weichinger wrote

> Hi, Kris,
> 
> on Dienstag, 20. Juli 2004 at 23:14 you wrote to amanda-users:
> 
> KV> The box is running redhat 9 with 2.4.20 kernel and ext3 filesystem.
> KV> Below is the most recent sendsize.debug
> 
> KV> sendsize[27747]: time 11114.784: Total bytes written: 429923983360 (400GB, 37MB/s)
> 
> ok ...
> 
> KV> sendsize[27747]: time 18815.342: Total bytes written: 69237104640 (64GB, 8.6MB/s)
> 
> not ok ---

Actually, both of those are *very* slow.  Remember, those are estimates, 
and they "write" to /dev/null.  When tar does that, it doesn't actually 
read the bits off the spindles, it just stats the files.  On my big 
(Linux) file servers, I get estimate rates on the order or GB/s -- up to 
80GB/s in some cases.  One difference, though, is that I'm using XFS.
Maybe I am missing something here, but do I need to have the estimates? Does something depend on this? If I just ripped this out somehow (no idea how I would go about doing this) then waiting 7 hours for an estimate would no longer be a problem... right?

> I would:
> 
> - split venus:/home into several DLEs (via exclude/include)

I don't know that this will help.

> - exclude unnecessary subdirs/files (./qa/build-main-branch-rfexamples/rfexamples-20040719/customer_test/Nestoras4/Freq
> Domain/Linux_temp-g seems like a candidate to me)

That's a good idea, of course.

> This would spawn several sendsize-processes in parallel ...

Actually, if you look at sendsize*debug, the estimates occur sequentially, 
not in parallel.  ICBW, but that's how it looks to me.

Kris, I think that you need to some performance testing/optimizing of your 
system.  What controllers are you using? 
I am using a 3ware 12 port RAID card. Initially when I set the card up I did some benchmarking and the read/write speeds to the drives being backed up were excellent, what they were doesn't come to mind at this moment. I am trying not to take this machine down for any reason as it is a HUGE hassle, but it looks like I am going to have to.
 Have you tested with bonnie++ 
and/or tiobench?  Are there mount parameters to ext3 you can play with 
(data="" comes to mind)? 
I tried using   noatime  for the run last night and that didn't seem to help worth squat. :( It seems as if i set data="" I might as well turn off journaling completely because there is no guarantee that old data from the journal wont end up getting written back to the disk in the event of the system going down. However, would this really speed things up? Dramatically?
 You may also want to spend some time on 
bugzilla and see if there's some other kernel-foo you can apply to RH's 
kernel (I assume you're using RH's kernel -- if not vanilla 2.4.20 is 
awfully old...) to speed up disk stuff.
I am using redhat's kernel 2.4.20-20.9smp
<Prev in Thread] Current Thread [Next in Thread>