FWIW, I have the
same issue under an HP EVA8000. I'm not really certain if directio is a
solution as I have only seen the tur checker being used with an
EVA.
Daniel
---------------------------------------------------------------------------------------------
Date: Tue, 22 Jul
2008 16:55:27 +0200
From: Hannes Reinecke <hare@xxxxxxx>
Subject: Re: Losing paths
To: device-mapper development <dm-devel@xxxxxxxxxx>
Message-ID: <4885F4DF.8010000@xxxxxxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
From: Hannes Reinecke <hare@xxxxxxx>
Subject: Re: Losing paths
To: device-mapper development <dm-devel@xxxxxxxxxx>
Message-ID: <4885F4DF.8010000@xxxxxxx>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Hi
John,
Romanowski, John
(OFT) wrote:
> Hi,
> We had similar problem last year using sles9 and SVC 4.2.0.2, as you describe: adding/deleting a LUN causes
> brief path failures for the host's remaining, unaffected LUNs.
>
> We were using tur checker and it turned out that while adding/deleting a LUN (and some other admin tasks)
> the SVC does not respond well to test-unit-ready tur requests; but it responds perfectly well to normal read
> commands. I opened IBM PMR 43118 on that if you want to ask the SVC folks about it.
>
> Workaround for us was to use readsector0 instead of tur as multipath path checker.
>
> Recent post here (see July 8, 2008) said multipath-tools is deprecating readsector0, and to use directio as
> path checker, but directio was said to be much slower than tur, implying tur was better replacement than
> directio for readsector0.
>
Only for those cases where no actual read-access is necessary.
> Not sure what deprecating readsector0 means for us SVC users.
>
It means you should be using directio there.
> Hi,
> We had similar problem last year using sles9 and SVC 4.2.0.2, as you describe: adding/deleting a LUN causes
> brief path failures for the host's remaining, unaffected LUNs.
>
> We were using tur checker and it turned out that while adding/deleting a LUN (and some other admin tasks)
> the SVC does not respond well to test-unit-ready tur requests; but it responds perfectly well to normal read
> commands. I opened IBM PMR 43118 on that if you want to ask the SVC folks about it.
>
> Workaround for us was to use readsector0 instead of tur as multipath path checker.
>
> Recent post here (see July 8, 2008) said multipath-tools is deprecating readsector0, and to use directio as
> path checker, but directio was said to be much slower than tur, implying tur was better replacement than
> directio for readsector0.
>
Only for those cases where no actual read-access is necessary.
> Not sure what deprecating readsector0 means for us SVC users.
>
It means you should be using directio there.
Thanks for the
information, I'll see to have it included in SLES10.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Markus Rex, HRB 16746 (AG Nürnberg)
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