On 11/11/2009 10:01 AM, Leslie Rhorer wrote:
>
>>> If you have a temporary space for your data, I'd suggest you move it
>>> out and go for an internal bitmap solution. It certainly beats the
>>> patch work you're going to have to do on the startup scripts (and
>>> every time you update mdadm, or the distro).
>>>
>> There should be no need to move the data off - you can add an internal
>> bitmap using the --grow option. An internal bitmap does have more of an
>> overhead than an external one though.
>
> I thought I remembered reading in the man page than an internal
> bitmap could only be added when the array was created? Is that incorrect?
Yes, very incorrect. You can use grow to add an internal bitmap later,
the only limitation is that the bitmap must be small enough to fit in
the reserved space around the superblock. It's in the case that you
want to create some super huge, absolutely insanely fine grained bitmap
that it must be done at raid device creation time and that's only so it
can reserve sufficient space for the bitmap.
--
Doug Ledford <dledford@xxxxxxxxxx>
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