Veritas-bu

[Veritas-bu] Maximzing Gigabit Performance

2006-08-27 04:46:18
Subject: [Veritas-bu] Maximzing Gigabit Performance
From: jpiszcz at lucidpixels.com (Justin Piszcz)
Date: Sun, 27 Aug 2006 04:46:18 -0400 (EDT)

On Sat, 26 Aug 2006, Bahnmiller, Bryan wrote:

> Martin,
>
>
>
>  We were trying to do some performance tuning to see if we could get
> our LTO2 and LTO3 drives working more effectively. The most interesting
> thing I ran across was setting the fragment size on the storage unit. If
> you don't have any fragment size, that is the best. Given our
> circumstances we need to run with fragment sizes on our storage units.
> For testing purposes, the system was configured with NET_BUFFER_SZ =
> 262144, SIZE_DATA_BUFFERS = 262144 and NUMBER_DATA_BUFFERS = 16. The
> test data was generated by the HPCreateData tool and is supposed to be
> 2-1 compressible data.
>
>
>
>  What I found was that a 1 GB fragment size does not even give an LTO2
> drive enough time to come up to its rated speed. It writes for about 6 -
> 10 seconds, then has to write the EOF marker, then repositions the tape.
> Similarly the LTO3 drive does not get up to speed either.
>
>
>
>  Here's a quick chart of findings. The media server was an IBM P5/550
> with 4 CPUs 8GB RAM with 2 LPARs, each getting half the resources.
>
>
>
> LTO2
>
> Fragment Size         Speed
>
> 1 GB                  35 MB/s
>
> 2 GB                  40 MB/s
>
> 4 GB                  43 MB/s
>
> 6 GB                  53 MB/s
>
> 7 GB                  52 MB/s
>
> 8 GB                  44 MB/s
>
> 10 GB                 41 MB/s
>
> 12 GB                 49 MB/s
>
> No fragment           58 MB/s   (approximately LTO2 max speed at 2-1
> compression)
>
>
>
> LTO3
>
> 1 GB                  41 MB/s
>
> 2000 MB               44 MB/s
>
> 2 GB                  55 MB/s
>
> 4 GB                  51 MB/s
>
> 5000 MB               49 MB/s
>
> 6 GB                  58 MB/s
>
> 8 GB                  63 MB/s
>
> 10000 MB              79 MB/s
>
> 10 GB                 81 MB/s
>
> 12 GB                 61 MB/s
>
> No fragment           82 MB/s
>
>
>
>  I think the upper limits on my LTO3 speed are due to my inability to
> get the AIX tuning correct. My disk subsystem should be able to supply
> data at roughly 130 MB/s and the LTO3 drives should be able to handle
> that. Something is not right on my tuning.
>
>
>
>  But I did find it very interesting as to the impact that fragment size
> can have on the tape performance.
>
>
>
> Bryan Bahnmiller
>
> ISD Business Continuity
>
> Pier 1 Imports, Inc
>
> Fort Worth, TX
>
>
>
> ________________________________
>
> From: veritas-bu-bounces at mailman.eng.auburn.edu
> [mailto:veritas-bu-bounces at mailman.eng.auburn.edu] On Behalf Of Martin,
> Jonathan (Contractor)
> Sent: Friday, August 25, 2006 11:58 AM
> To: veritas-bu at mailman.eng.auburn.edu
> Subject: [Veritas-bu] Maximzing Gigabit Performance
>
>
>
> All, we're tying to maximize our throughput across gigabit Ethernet and
> playing with the buffers etc to try and get faster numbers.
>
>
>
> Client Buffer
>
> NET_BUFFER_SIZE
>
> NUMBER_DATA_BUFFERS_DISK
>
> SIZE_DATA_BUFFERS_DISK
>
> KB/sec
>
> 256
>
> 262144
>
> ---
>
> ---
>
> 34000
>
> 256
>
> 2097152
>
> ---
>
> ---
>
> 39500
>
> 256
>
> 2097152
>
> 16
>
> ---
>
> 37000
>
> 256
>
> 2097152
>
> 16
>
> 262144
>
> 36000
>
> 512
>
> 2097152
>
> 64
>
> 262144
>
> 40480
>
> 1024
>
> 2097152
>
> 64
>
> 262144
>
> 37608
>
> 1024
>
> 4194304
>
> 64
>
> 262144
>
> 37473
>
>
>
>
>
> Netbackup 5.1 Client --> Gigabit Copper --> Cisco Switch --> Gigabit
> Fiber --> Media Server --> Direct Attached SCSI 320 Drive
>
>
>
> Here's the results of some testing from this morning on one of my
> fastest servers (as far as disk/processor/memory) are concerned.  It
> looks like my "sweet spot" is about 40MB/sec through Netbackup.  If I
> try and FTP several files directly from this server to the Media Server
> via the same network config to disk I can get close to 60MB/sec.  Am I
> missing some setting here?  Why can't I get even close to duplicating
> the 60MB/sec I get via FTP?  My perfmon shows the server's nic only
> pushing 45MB/sec or less with drops in communication every 10 seconds or
> so.  I'm missing something, any ideas?
>
>
>
> -Jonathan
>
>

Very interesting findings, but the purpose of the frag bit is to increase 
the speed of restores, how does it affect the restoration speed?

Justin.