Re: Async I/O on AIX

From: koert54 <nospam_at_spam.com>
Date: Tue, 17 Sep 2002 20:04:05 GMT
Message-ID: <VULh9.121160$8o4.17480@afrodite.telenet-ops.be>

"tingl" <tlam15_at_hotmail.com> wrote in message news:f487699f.0209171107.4d30611d_at_posting.google.com... > "Chuck" <chuckh_at_softhome.net> wrote in message news:<am7fea$3aun4$1_at_ID-85580.news.dfncis.de>...
> > "tingl" <tlam15_at_hotmail.com> wrote in message
> > news:f487699f.0209161411.4fd16379_at_posting.google.com...
> > > "Chuck" <chuckh_at_softhome.net> wrote in message
> > news:<am537c$2pm0o$1_at_ID-85580.news.dfncis.de>...
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> > > > The Oracle 8i Administrator's Reference for AIX says to set the max
> > > > i/o servers to "at least 10*(number of disks that AIO accesses
> > > > simultaneously)". Can someone clarify whether they mean physical
> > > > disks, or logical filesystems? TIA
> > > >
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> > > Physical disks.

> >

> > Just to be sure then, if I have 15 file systems that are concurrently in
> > use, each of which is a 3 volume RAID logical device, I need 450 async
i/o
> > servers. Is that correct? It just seems like an awful lot.

> >

> > TIA

>
> Yes, it does seem like a large number. This is only provided as a
> guideline. Actual usage may vary from system to system. You have to
> experiment a little.
>
> For example, you could set max_aios to 450 and min_aios to 200. When
> your system starts, it will start 200 aios and the number increases on
> demand up to max_aios. After a period of time, you can issue this
> command to see the peak number of aios started since the system
> reboot.

>
> pstat -a |grep aio|wc -l
>

> It should give you an idea how many aios you need. Make sure you don't > run low on memory.

Indeed ! If I remember correctly an aios takes about 8-10Mb !

>
>
> Tony

Received on Tue Sep 17 2002 - 15:04:05 CDT