Re: mdstat reporting (superblock & status side-by-side). Can it be changed ?

[Roman Mamedov <rm@romanrm.net>]

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On Sun, 13 Sep 2015 12:58:25 -0500
"David C. Rankin" <drankinatty@suddenlinkmail.com> wrote:

>    After looking at the output of /proc/mdstat many times, there is one 'human 
> factors' (human nature) bit of difficulty with the order of the output 
> (especially with a standard 2-disk raid1 array and 1.2 superblock:
> 
> md1 : active raid1 sda7[2] sdb7[1]
>        52396032 blocks super 1.2 [2/2] [UU]
>                              ^^^^^^^^^
> 
>    When scanning the information quickly to insure you do NOT have 1/2 disks 
> active in the array, you run into the version and disk information side-by-side.
> 
>    "1.2 [2/2]"
> 
>    Which naturally causes a short "huh?..., OK" double-take.

For me it does not. 1.2 is clearly different from 1/2, and the actual 2/2
that you have is even enclosed in brackets to stand out more prominently.

>    Is there any way from a user standpoint (short of "read a b c d e f"; echo 
> "$c $d $a $b $e $f"), to rearrange the order the information is reported as:
> 
> md1 : active raid1 sda7[2] sdb7[1]
>        super 1.2 52396032 blocks [2/2] [UU]
> 
>    That simple change makes glancing down the right-side of the information much 
> easier on the brain....

If you want to simplify the mental processing, just look for any "_"s in the
string of "U"s which is also conveniently placed at the end of the line. In a
partially down RAID1 you'd have [U_] or [_U] there, which is very noticeable
compared to the usual [UU].

>    I don't think this was ever a concern prior to the 1.2 superbock and I'm not 
> sure it warrants any brainpower now. However, it was something that stood out to 
> me, so I thought I would pass it along.

I don't think it's justified to randomly change things around which many shell
scripts and the like are quite likely to depend on, just out of a personal
preference.

-- 
With respect,
Roman

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