From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Lieven <pl@kamp.de>, Michael Tokarev <mjt@tls.msk.ru>,
ronnie sahlberg <ronniesahlberg@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-devel <qemu-devel@nongnu.org>,
Stefan Hajnoczi <stefanha@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] block/iscsi: use 16 byte CDBs only when necessary
Date: Tue, 17 Jun 2014 13:46:46 +0200 [thread overview]
Message-ID: <53A02AA6.2060006@redhat.com> (raw)
In-Reply-To: <53A02867.7090400@kamp.de>
Il 17/06/2014 13:37, Peter Lieven ha scritto:
> On 17.06.2014 13:15, Paolo Bonzini wrote:
>> Il 17/06/2014 08:14, Peter Lieven ha scritto:
>>>>
>>>
>>> BTW, while debugging a case with a bigger storage supplier I found
>>> that open-iscsi seems to do exactly this undeterministic behaviour.
>>> I have a 3TB LUN. If I access < 2TB sectors it uses READ10/WRITE10 and
>>> if I go beyond 2TB it changes to READ16/WRITE16.
>>
>> Isn't that exactly what your latest patch does for >64K sector writes? :)
>
> Not exactly, we choose the default by checking the LUN size. 10 Byte for
> < 2TB and 16 Byte otherwise.
Yeah, I meant introducing the non-determinism.
> My latest patch makes an exception if a request is bigger than 64K
> sectors and
> switches to 16 Byte requests. These would otherwise end in an I/O error.
It could also be split at the block layer, like we do for unmap. I
think there's also a maximum transfer size somewhere in the VPD, we
could to READ16/WRITE16 if it is >64K sectors.
Paolo
next prev parent reply other threads:[~2014-06-17 11:47 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-04 13:47 [Qemu-devel] [PATCH] block/iscsi: use 16 byte CDBs only when necessary Peter Lieven
2014-06-04 14:00 ` ronnie sahlberg
2014-06-04 14:43 ` Peter Lieven
2014-06-04 14:54 ` ronnie sahlberg
2014-06-05 9:12 ` Michael Tokarev
2014-06-05 9:27 ` Peter Lieven
2014-06-17 6:14 ` Peter Lieven
2014-06-17 11:15 ` Paolo Bonzini
2014-06-17 11:37 ` Peter Lieven
2014-06-17 11:46 ` Paolo Bonzini [this message]
2014-06-17 11:50 ` Peter Lieven
2014-06-17 13:45 ` Peter Lieven
2014-09-01 15:21 ` Peter Lieven
2014-09-02 15:28 ` ronnie sahlberg
2014-09-02 18:14 ` Peter Lieven
2014-09-02 19:30 ` Peter Lieven
2014-09-03 8:09 ` Peter Lieven
2014-09-03 12:31 ` Stefan Hajnoczi
2014-09-03 13:13 ` Peter Lieven
2014-09-03 14:17 ` ronnie sahlberg
2014-09-03 14:18 ` Paolo Bonzini
2014-09-03 14:48 ` ronnie sahlberg
2014-09-03 19:29 ` Peter Lieven
2014-06-04 15:31 ` Paolo Bonzini
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