From: Craig James <craig_james@emolecules.com>
To: Mike Smith <mike.smith@enterprisedb.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: 8x2.5" or 6x3.5" disks
Date: Tue, 29 Jan 2008 07:06:23 -0800
Message-ID: <479F40EF.6070802@emolecules.com> (raw)
In-Reply-To: <51494DB187D98F4C88DBEBF1F5F6D42303EC56C9@edb06.mail01.enterprisedb.com>
References: <285fb20801281125k641902feo8d74b1c68640d94b@mail.gmail.com>
<51494DB187D98F4C88DBEBF1F5F6D42303EC56C9@edb06.mail01.enterprisedb.com>
Mike Smith wrote:
> I’ve seen a few performance posts on using different hardware
> technologies to gain improvements. Most of those comments are on raid,
> interface and rotation speed. One area that doesn’t seem to have
> been mentioned is to run your disks empty.
> ...
> On the outside of the disk you get a lot more data per seek than on the
> inside. Double whammy you get it faster.
>
> Performance can vary more than 100% between the outer and inner tracks
> of the disk. So running a slower disk twice as big may give you more
> benefit than running a small capacity 15K disk full. The slower disks
> are also generally more reliable and mostly much cheaper.
> ...
> This is not very green as you need to buy more disks for the same amount
> of data and its liable to upset your purchasing department who won’t
> understand why you don’t want to fill your disks up.
So presumably the empty-disk effect could also be achieved by partitioning, say 25% of the drive for the database, and 75% empty partition. But in fact, you could use that "low performance 75%" for rarely-used or static data, such as the output from pg_dump, that is written during non-peak times.
Pretty cool.
Craig
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To: pgsql-performance@postgresql.org
Cc: craig_james@emolecules.com, mike.smith@enterprisedb.com
Subject: Re: 8x2.5" or 6x3.5" disks
In-Reply-To: <479F40EF.6070802@emolecules.com>
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