Re: [Scst-devel] t10_dev_id collisions

[Vladislav B. <vs...@vl...>]

Hi Bart,

Bart Van Assche, on 03/27/2011 04:04 PM wrote:
> On Sun, Mar 27, 2011 at 4:35 AM, Steven Umbehocker
> <ste...@os...> wrote:
>>
>> I think someone noted it before recently, but it's worth mentioning
>> again.  When you select the t10_dev_id for your device be sure that the
>> unique part of whatever identifier you choose is in the first 8
>> characters as Windows MPIO doesn't look at the whole thing.    For
>> example, two separate vdisks/LUNs with t10 ids set as "aaaabbbb1234" and
>> "aaaabbbb5678" will get mistakenly combined by Windows MPIO into one
>> device because it's ignoring everything past the initial "aaaabbbb".. so
>> using this example again, flipping those IDs around like so
>> "1234aaaabbbb" and "5678aaaabbbb" will make it so that they're properly
>> identified.. the trailing characters "bbbb" are ignored.
> 
> Hi Vlad,
> 
> What do you think about the patch below (not tested yet) ? It swaps the
> generated device ID number and the device name in the generated t10_dev_id.
> That change should reduce considerably the probability of t10_dev_id clashes
> like the one described above.

It's a good idea! I'm thinking about it for some time. Since I don't
like random_values table as well I took a chance to also get rid of it
and make the random value as crc32 from the name. It gives exactly 8
characters we need.

Thanks,
Vlad