Re: Neat trick

blockdev is a Linux utility for examining block devices (such as
/dev/sda) and for configuring certain aspects of how I/O is performed
on those devices. See http://man.he.net/man8/blockdev.

Will

On 15 September 2010 15:33, Arvind Sharma <arvind321(at)yahoo(dot)com> wrote:
> Hi Mladen,
>
> Which attribute in the postgresql.conf file this is set ?
>
> I am running CentOS Linux, PG 8.4
>
> Thanks!
> Arvind
>
>
> ________________________________
> From: Mladen Gogala <mgogala(at)vmsinfo(dot)com>
> To: "pgsql-novice(at)postgresql(dot)org" <pgsql-novice(at)postgresql(dot)org>
> Sent: Tue, September 14, 2010 2:30:28 PM
> Subject: [NOVICE] Neat trick
>
> I figured out how to speed up the sequential scans using "blockdev" command.
> Essentially, this increases the read-ahead on the underlying block device
> for the file system. It will change the read-ahead value for the entire
> disk, even if there are several partitions on the disk.  The results are
> very promising. Unfortunately, I didn't take baseline numbers and measure
> the effect with precision, but the look of it is that things are much faster
> with the read-ahead set to 2048 instead of the default 256. The read-ahead
> is measured in sectors read ahead by the OS. The OS is Red Hat Linux, EL
> 5.5.
>
> --
> Mladen Gogala Sr. Oracle DBA
> 1500 Broadway
> New York, NY 10036
> (212) 329-5251
> http://www.vmsinfo.com The Leader in Integrated Media Intelligence Solutions
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>
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