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Message-ID: <4C4D53DA.3070909@gmail.com>
Date: Mon, 26 Jul 2010 11:22:34 +0200
From: Yeb Havinga <yebhavinga@gmail.com>
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To: Greg Smith <greg@2ndquadrant.com>
CC: pgsql-performance@postgresql.org
Subject: Re: Testing Sandforce SSD
References: <4C4A9452.9070100@gmail.com> <4C4B1F84.5030306@2ndquadrant.com>
	<4C4C83DF.3010703@gmail.com>
In-Reply-To: <4C4C83DF.3010703@gmail.com>
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Yeb Havinga wrote:
> Greg Smith wrote:
>> Put it on ext3, toggle on noatime, and move on to testing.  The 
>> overhead of the metadata writes is the least of the problems when 
>> doing write-heavy stuff on Linux.
> I ran a pgbench run and power failure test during pgbench with a 3 
> year old computer
>
On the same config more tests.

scale 10 read only and read/write tests. note: only 240 s.

starting vacuum...end.
transaction type: SELECT only
scaling factor: 10
query mode: prepared
number of clients: 10
duration: 240 s
number of transactions actually processed: 8208115
tps = 34197.109896 (including connections establishing)
tps = 34200.658720 (excluding connections establishing)

yeb@client45:~$ pgbench -c 10 -l -M prepared -T 240 test
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 10
query mode: prepared
number of clients: 10
duration: 240 s
number of transactions actually processed: 809271
tps = 3371.147020 (including connections establishing)
tps = 3371.518611 (excluding connections establishing)

----------
scale 300 (just fits in RAM) read only and read/write tests

pgbench -c 10 -M prepared -T 300 -S test
starting vacuum...end.
transaction type: SELECT only
scaling factor: 300
query mode: prepared
number of clients: 10
duration: 300 s
number of transactions actually processed: 9219279
tps = 30726.931095 (including connections establishing)
tps = 30729.692823 (excluding connections establishing)

The test above doesn't really test the drive but shows the CPU/RAM limit.

pgbench -c 10 -l -M prepared -T 3600 test
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 300
query mode: prepared
number of clients: 10
duration: 3600 s
number of transactions actually processed: 8838200
tps = 2454.994217 (including connections establishing)
tps = 2455.012480 (excluding connections establishing)

------
scale 2000

pgbench -c 10 -M prepared -T 300 -S test
starting vacuum...end.
transaction type: SELECT only
scaling factor: 2000
query mode: prepared
number of clients: 10
duration: 300 s
number of transactions actually processed: 755772
tps = 2518.547576 (including connections establishing)
tps = 2518.762476 (excluding connections establishing)

So the test above tests the random seek performance. Iostat on the drive 
showed a steady just over 4000 read io's/s:
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          11.39    0.00   13.37   60.40    0.00   14.85
Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s 
avgrq-sz avgqu-sz   await  svctm  %util
sda               0.00     0.00 4171.00    0.00 60624.00     0.00    
29.07    11.81    2.83   0.24 100.00
sdb               0.00     0.00    0.00    0.00     0.00     0.00     
0.00     0.00    0.00   0.00   0.00

pgbench -c 10 -l -M prepared -T 24000 test
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 2000
query mode: prepared
number of clients: 10
duration: 24000 s
number of transactions actually processed: 30815691
tps = 1283.979098 (including connections establishing)
tps = 1283.980446 (excluding connections establishing)

Note the duration of several hours. No long waits occurred - of this 
last test the latency png is at http://yfrog.com/f/0vlatencywp/ and the 
TPS graph at http://yfrog.com/f/b5tpsp/

regards,
Yeb Havinga