Talk about your IO system a bit.  There might be obvious ways to improve.

What System/Motherboard are you using?
What Controller Cards are you using?
What kind of Disks do you have (SATA, SCSI 7.6k 10k 15k)
What denominations (9, 18, 36, 72, 143, 80, 160, 200 240Gig)?
What kind of RAIDs do you have setup (How many drives what stripe sizes, how many used for what).
What levels of RAID are you using (0,1,10,5,50)?

With good setup, a dual PCI-X bus motherboard can hit 2GB/sec and thousands of transactions  to disk if you have a controller/disks that can keep up.  That is typicaly enough for most people without resorting to SSD.

Alex Turner

On 10/4/05, Emil Briggs <[EMAIL PROTECTED]> wrote:

I have an application that has a table that is both read and write intensive.
Data from iostat indicates that the write speed of the system is the factor
that is limiting performance. The table has around 20 columns and most of the
columns are indexed. The data and the indices for the table are distributed
over several mirrored disk partitions and pg_xlog is on another. I'm looking
at ways to improve performance and besides the obvious one of getting an SSD
I thought about putting the indices on a ramdisk. That means that after a
power failure or shutdown I would have to recreate them but that is
acceptable for this application. What I am wondering though is whether or not
I would see much performance benefit and if there would be any startup
problems after a power down event due to the indices not being present. Any
insight would be appreciated.


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