Re: quorum question

ah ha. so i was initially correct (see original post). the confusion was
from where the 2 came from as in, was it being specified somewhere manually.

i know that for a two disk system when one fails the mirrored vg goes down
due to the assignment of VGDA's over the pv's (see my original post). Thus
all that QUORUM: 2
line is saying is that quorum checking has been enabled and because of that,
2 disks are requred for quorum (given the situation of haveing only two
drives in the volume group). if it were a three disk system then i would
guess that the line would be something like QUORUM 1. for in a three disk
system each disk has its own VGDA and there is one set of these on every
drive thus losing one drive still gives 66% of all VGDA's available and thus
51% of the quorum is met.

silly - i should have seen that.

cheers
moth



"Dan Foster" <usenet@xxxxxxxxxxx> wrote in message
news:slrndsquee.2tp.usenet@xxxxxxxxxxxxxxxxxxxx
> In article <dqjt67$c8j$1@xxxxxxxxxxxxxxxxxxxxxxxxxx>, rancid moth
> <rancidmoth@xxxxxxxxx> wrote:
>>
>> thanks for the advice. however do you know exactly what the
>>
>> QUORUM: 2
>>
>> line in the lsvg rootvg display refers to?
>
> It means that two drives are required to achieve quorum.
>
> If one drive fails while this is set to 2, the system will intentionally
> panic, because quorum requires 1/2 of all drives + 1.
>
> Sample quorum calculation:
>
> 2 drive setup: 1 drive fail, quorum requirement is 1/2 of 2.. that's 1
> drive. Plus one drive. So, 2 drives is required to maintain quorum.
>
> If only 1 is working, system automatically panics because 1 working
> drive is less than minimum quorum required of 2 working drives.
>
> To correct that, you need to do the two steps mentioned earlier.
>
> The quorum mechanism is designed to prevent potential data corruption or
> loss, but it does not make much sense in a two drive mirrored setup.
>
> So the standard advice is to disable quorum if you have that setup --
> which you do.
>
> -Dan


.

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