From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andreas Klauer <Andreas.Klauer@metamorpher.de>
Subject: Re: "bitmap" line in /proc/mdstat
Date: Fri, 14 Oct 2016 19:43:14 +0200
Message-ID: <20161014174314.GA24243@metamorpher.de>
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To: Peter Sangas <pete@wnsdev.com>
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On Fri, Oct 14, 2016 at 10:32:47AM -0700, Peter Sangas wrote:
> I installed Ubuntu 16.04 and used the installer to create a RAID1 some of the mds had bitmaps and some did not.

Small ones (/boot, swap) might not get a bitmap by default.
According to the manpage it needs 100G or larger.

|       -b, --bitmap=
|[...]
|              When  creating  an  array  on  devices which are 100G or larger,
|              mdadm automatically adds an internal bitmap as it  will  usually
|              be beneficial.  This can be suppressed with --bitmap=none .



Regards
Andreas Klauer