[Veritas-bu] Maximzing Gigabit Performance
2006-08-26 20:40:36
Subject: |
[Veritas-bu] Maximzing Gigabit Performance |
From: |
BBahnmiller at pier1.com (Bahnmiller, Bryan) |
Date: |
Sat, 26 Aug 2006 19:40:36 -0500 |
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
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