| From: | "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net> |
|---|---|
| To: | Barry Lind <barry(at)xythos(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: problems with new vacuum (??) |
| Date: | 2002-01-02 14:49:58 |
| Message-ID: | 200201021442.g02EgZZ25397@neuromancer.ctlno.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Tuesday 01 January 2002 11:23 pm, Barry Lind wrote:
> Tom,
>
> The platform is Redhat 7.0 with a 2.2.19 kernal.
Is this and IDE based system? If so do you have the drives running in DMA
mode?
What are the results of "/sbin/hdparm /dev/hd(?)" (a,b,c,d ... which ever
drive you are running the database on.)
The 2.2 linux kernel defaults to DMA off. You can try to enable dma by
issuing /sbin/hdparm -d1 /dev/hd(?) You can also test the disk speed with
/sbin/hdparm -tT /dev/hd(?).
In my experience enabling this feature can make a huge improvement in I/O
intensive applications. Other options can help also, but I find dma to have
the largest impact. I find linux almost unusable without it.
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