On Wednesday November 9, andyliebman@xxxxxxxxxxxxx wrote:
> > Okay,
> >
> > PLEASE somebody who knows answer the following:
> >
> > 1) what is the difference between running
> >
> > mdadm -A -ayes 1/dev/md1--uuid=xxxxx /dev/sd*
> >
> > and
> >
> > mdadm -A -amd 1/dev/md1 --uuid=xxxxx /dev/sd*
> >
> >
> > In other words, how do the "yes" and "md" options behave
> > differently.
From 'man mdadm'
-a, --auto{=no,yes,md,mdp,part,p}{NN}
Instruct mdadm to create the device file if needed, possibly allocat-
ing an unused minor number. "md" causes a non-partitionable array to
be used. "mdp", "part" or "p" causes a partitionable array (2.6 and
later) to be used. "yes" requires the named md device to have a from
this. See DEVICE NAMES below.
Hmmm. there is some text missing there. It should read:
-a, --auto{=no,yes,md,mdp,part,p}{NN}
Instruct mdadm to create the device file if needed, possibly
allocating an unused minor number. "md" causes a non-partition-
able array to be used. "mdp", "part" or "p" causes a partition-
able array (2.6 and later) to be used. "yes" requires the named
md device to have a 'standard' format, and the type and minor
number will be determined from this. See DEVICE NAMES below.
(typo in the mdadm.8 source file).
Does that help?
> >
> >
> > 2) If you create an array /dev/md0 with mdadm, is there any reason why
> > you shouldn't start it as /dev/md1?
No technical reason. This works perfectly.
> >
> > The second option above (-amd 1) would NOT start an array that was created
> > as /dev/md0 (under an older mdadm -- 1.8.? ) whereas the first option
> > (-ayes /dev/md1) had no difficulty.
> >
> > Thank you.
> > Andy Liebman
> >
> >
>
> Sorry, my bad:
>
> I meant to give as my examples:
>
> mdadm -A -amd 1 --uuid=xxxxx /dev/sd*
This is wrong. It will create a device files called '1' in the
current directory (assuming it works at all).
>
> and
>
> mdadm -A -ayes /dev/md1 --uuid=xxxxx /dev/sd*
Given that /dev/md1 is a 'standard' format name, this will have the
same effect as "-amd /dev/md1". You only get the difference when you
want to use a name like "/dev/md/home" or "/dev/swap", in which case,
"-ayes" isn't allowed as mdadm cannot differentiate between
partitioned and not.
NeilBrown
-
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
