From: | Janning <ml(at)planwerk6(dot)de> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Disk performance |
Date: | 2010-06-15 12:59:38 |
Message-ID: | 201006151459.38370.ml@planwerk6.de |
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Thread: | |
Lists: | pgsql-general |
Hi all,
as we encountered some limitations of our cheap disk setup, I really would
like to see how cheap they are compared to expensive disk setups.
We have a 12 GB RAM machine with intel i7-975 and using
3 disks "Seagate Barracuda 7200.11, ST31500341AS (1.5 GB)"
One disk for the system and WAL etc. and one SW RAID-0 with two disks for
postgresql data.
Now I ran a few test as described in
http://www.westnet.com/~gsmith/content/postgresql/pg-disktesting.htm
# time sh -c "dd if=/dev/zero of=bigfile bs=8k count=3000000 && sync"
3000000+0 records in
3000000+0 records out
24576000000 bytes (25 GB) copied, 276.03 s, 89.0 MB/s
real 4m48.658s
user 0m0.580s
sys 0m51.579s
# time dd if=bigfile of=/dev/null bs=8k
3000000+0 records in
3000000+0 records out
24576000000 bytes (25 GB) copied, 222.841 s, 110 MB/s
real 3m42.879s
user 0m0.468s
sys 0m18.721s
IMHO it is looking quite fast compared to the values mentioned in the article.
What values do you expect with a very expensive setup like many spindles,
scsi, raid controller, battery cache etc. How much faster will it be?
Of yourse, you can't give me exact results, but I would just like to get a an
idea about how much faster an expensive disk setup could be.
Would it be like 10% faster, 100% or 1000% faster? If you can give me any
hints, I would greatly appreciate it.
kind regards
Janning
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