Re: Proposed enhancement to mdadm: Allow "--write-behind=" to be done in grow mode.

[Neil Brown <neilb@suse.de>]

On Tuesday July 3, ian@beware.dropbear.id.au wrote:
> There doesn't seem to be any designated place to send bug reports and
> feature requests to mdadm, so I hope I am doing the right thing by
> sending it here.

Yes. Exactly the right thing, thanks.

I have applied the patch and pushed it out into .git.  It will appear
in the next release of mdadm.

Thank,
NeilBrown

> 
> I have a small patch to mdamd which allows the write-behind amount to be
> set a array grow time (instead of currently only at grow or create
> time). I have tested this fairly extensively on some arrays built out of
> loop back devices, and once on a real live array. I haven't lot any data
> and it seems to work OK, though it is possible I am missing something.
> 
> --- mdadm-2.6.1/mdadm.c.writebehind	2006-12-21 16:12:50.000000000 +1030
> +++ mdadm-2.6.1/mdadm.c	2007-06-30 13:16:22.000000000 +0930
> @@ -827,6 +827,7 @@
>  			bitmap_chunk = bitmap_chunk ? bitmap_chunk * 1024 : 512;
>  			continue;
>  
> +		case O(GROW, WriteBehind):
>  		case O(BUILD, WriteBehind):
>  		case O(CREATE, WriteBehind): /* write-behind mode */
>  			write_behind = DEFAULT_MAX_WRITE_BEHIND;
> 
> 
> -- 
> Ian Dall <ian@beware.dropbear.id.au>