[Stgt-devel] disabling write cache?

[Mark Harvey]

Re: http://stgt.berlios.de/patches/0001-iscsi-fix-sense-handling.patch

So thats where it is...

I've been scratching my head over this for ages.
This (sending sense data on SAM_STAT_GOOD)

On Wed, Jun 25, 2008 at 12:10 PM, FUJITA Tomonori
<fujita.tomonori at lab.ntt.co.jp> wrote:
> On Thu, 19 Jun 2008 13:54:15 +0200
> Tomasz Chmielewski <mangoo at wpkg.org> wrote:
>
>> Is there a way to disable write caching when using tgtd as a target?
>>
>> Right now, it seems to be impossible (at least I didn't find an option
>> in documentation nor sources) and setting it on the initiator fails:
>>
>> initiator# sdparm /dev/sda
>>      /dev/sda: IET       VIRTUAL-DISK  0001
>> Caching (SBC) mode page:
>>    WCE         1  [cha: y, def:  1, sav:  1]
>>    RCD         0  [cha: n, def:  0, sav:  0]
>> (...)
>>
>> initiator# sdparm --set WCE=0 /dev/sda
>>      /dev/sda: IET       VIRTUAL-DISK  0001
>> change_mode_page: failed setting page: Caching (SBC)
>
> I've uploaded two patches:
>
> http://stgt.berlios.de/patches/0001-iscsi-fix-sense-handling.patch
> http://stgt.berlios.de/patches/0002-sbc-add-WCE-support-to-bs_rdwr.patch
>
> With the patches, you can disable write caching in the following way:
>
> tgtadm --lld iscsi --op update --mode logicalunit --tid 1 --lun 1 --params mode_page=8:0:18:0x10:0:0xff:0xff:0:0:0xff:0xff:0xff:0xff:0x80:0x14:0:0:0:0:0:0
>
> Note that you need to modify tid and lun in your environment.
>
>
> Shortly, I'll let you control write caching via sdparm too.
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