WRITE_AND_VERIFY doubt

Flavio Junior billpp at gmail.com
Fri May 8 11:41:56 PDT 2009


Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r0905084_f.htm">HTML-formatted message</a>

Hi Konrad, thanks for your answer, but...
I've already configured multipath to group my 4 paths to same LUN as a
single device, the problem here is about 2 different LUN's.
These LUN's are different because it comes from distinct storages devices, I
want to group both because the contents is being replicated by DS4700
Enhanced Remote Mirror feature.
--
Flávio do Carmo Júnior
Florianópolis/SC, Brazil
On Fri, May 8, 2009 at 1:50 PM, Konrad Rzeszutek
<konrad at virtualiron.com>wrote:
> On Fri, May 08, 2009 at 12:52:28PM -0300, Flavio Junior wrote:
> > Hi folks, afternoon.
> >
> > I've a tad doubt when writing a simple code to sends a WRITE_AND_VERIFY
> > (0x2E) command to a scsi device.
> >
> > I need to do it to decide if this is a primary (and read-write) storage
> or a
> > secundary (and read-only) storage (ibm ds4700), and adjust my I/O
> MultiPath
>
> I was under the impression that the DS4700 was an RDAC device. Meaning
> you can use these settings:
>
>  device {
>	 vendor 	 "IBM"
>	 product	 "1814"
>	 hardware_handler    "1 rdac"
>	 path_grouping_policy	 group_by_prio
>	 prio		 "rdac"
>	 failback	 immediate
>	 path_checker	     rdac
>    }
>
>
> And it will detect whether your secondary paths are not in usage and
> call them 'ghost'.
>
> > priority accordingly, and i need to run it periodically to check if the
> > roles change.
> >
> > My doubt is, is there a area that I cant safety use this command without
> > risk to corrupt the data on disk? I'm not a really developer, just make
> some
>
> You will cause corruption.
> > researches and read some codes to assembly my own, here is the code:
> > http://pastebin.com/m22b06f04
> >
> >
> > O course, if there is a way more elegant to get this info I'll appreciate
> if
> > someone says me. :)
>
> I think using the right multipath.conf entry should do it.
> >
> >
> > Really thanks in advance and some sorries for english and dumb question.
> >
> >
> > --
> >
> > Flávio do Carmo Jùnior
> > Florianopolis/SC, Brazil
>



More information about the T10 mailing list