Re: RAID6 and crashes (reporting back re. --bitmap)

[Roman Mamedov <roman@rm.pp.ru>]

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On Mon, 14 Jun 2010 19:47:42 +1000
Neil Brown <neilb@suse.de> wrote:

> When you create an array an specify that a bitmap be added at the same time,
> there is more flexibility for size and location of the bitmap.  It can easily
> be more that 3K in that case.
> 
> So presumably this array was created with a bitmap, rather than created
> without a bitmap and had a bitmap added later with --grow.  Correct?

Yes, as far as I remember. However, it seems a bit unfortunate to have any
significant difference between adding the bitmap right when creating the
array, and adding it later. For that reason, I'd suggest reserving more space
in the metadata than 3K, even if the bitmap isn't requested - and even if it
won't be added later, then that space could prove useful for something else
that might require it later. Maybe 64, 128 or 256K - still miniscule compared
to the array size, and could provide some nice flexibility for the future.

-- 
With respect,
Roman

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