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From: "Michał Sawicz" <michal@sawicz.net>
To: Robin Hill <robin@robinhill.me.uk>
Cc: linux-raid@vger.kernel.org
Subject: Re: Best strategy to incrementally replace smaller HDDs [success story]
Date: Tue, 27 Sep 2011 10:37:48 +0200	[thread overview]
Message-ID: <1317112668.2758.43.camel@michal-laptop> (raw)
In-Reply-To: <1315578025.14468.18.camel@michal-laptop>

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Thanks again for all the pointers, I will now describe my workflow that
got me going with the new drives!

I'll try and do some ASCII-art [=== used space, --- space (not drives)
used for parity].


1. initial situation
   -----------------
    ~~1TB~~
sda |===========|
sdb |===========|
sdc |=====|
sdd |=====|
sde |=====|
sdf |=====|
sdg |=====|
sdh |=====|
sdi |-----|
sdj |-----|

md1       |=====|             -  2 x 1TB RAID0 == 2TB
md2 |=====|                   - 10 x 1TB RAID6 == 8TB


2. added 4 x 2TB drives
   --------------------
sdk             |           |
sdl             |           |
sdm             |           |
sdn             |-----------|

md3             |           | -  5 x 2TB RAID6 == 6TB (degraded)


3. moved part of md2 data onto md3
   ----------------------------------
sda |     ======|
sdb |     ======|
sdc |=====|
sdd |=====|
sde |=    |
sdf |     |
sdg |     |
sdh |     |
sdi |-----|
sdj |-----|
sdk             |===========|
sdl             |===========|
sdm             |===========|
sdn             |-----------|

md1       |=====|             -  2 x 1TB RAID0 == 2TB
md2 |==   |                   - 10 x 1TB RAID6 == 8TB
md3             |===========| -  5 x 2TB RAID6 == 6TB (degraded)


4. shrunk and removed drives from md2
   ----------------------------------
sda |     ======|
sdb |     ======|
sdc |=====|
sdd |=====|
sde |=    |
sdf |-----|
sdg                         |     |
sdh                         |     |
sdi                         |     |
sdj                         |     |
sdk             |===========|
sdl             |===========|
sdm             |===========|
sdn             |-----------|

md1       |=====|             -  2 x 1TB RAID0 == 2TB
md2 |==== |                   -  5 x 1TB RAID6 == 3TB (degraded)
md3             |===========| -  5 x 2TB RAID6 == 6TB (degraded)


5. new arrays to free the old 2TB drives
   and create an additional member for md4
   ---------------------------------------
sda             |===========|
sdb             |===========|
sdc |=====|
sdd |=====|
sde |=    |
sdf |-----|
sdg       |=====|
sdh       |=====|
sdi             |=====|
sdj                   |=====|
sdk             |           |
sdl             |           |
sdm             |-----------|
sdn             |-----------|

md4             |           | -  4 x 1TB RAID10 == 2TB (degraded)
md1       |=====|             -  2 x 1TB RAID0 == 2TB
md2 |==== |                   -  5 x 1TB RAID6 == 3TB (degraded)
md3             |=======    | -  7 x 2TB RAID6 == 10TB


6. Moved rest of the data from md2,
   dropped it and replaced a disk in md4
   -------------------------------------
sda             |===========|
sdb             |===========|
sdc             |=====|
sdg       |=====|
sdh       |=====|
sdj                   |=====|
sdk             |===========|
sdl             |           |
sdm             |-----------|
sdn             |-----------|

md4             |           | -  4 x 1TB RAID10 == 2TB (degraded)
md1       |=====|             -  2 x 1TB RAID0 == 2TB
md3             |=========  | -  7 x 2TB RAID6 == 10TB


And it only took two weeks! ;)

And again, thanks for all the pointers I got on the list, it all
happened without any data loss.
-- 
Michał (Saviq) Sawicz <michal@sawicz.net>

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      reply	other threads:[~2011-09-27  8:37 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-09 10:48 Best strategy to incrementally replace smaller HDDs Michał Sawicz
2011-09-09 12:34 ` David Brown
2011-09-09 14:12   ` Michał Sawicz
2011-09-09 13:13 ` Robin Hill
2011-09-09 14:20   ` Michał Sawicz
2011-09-27  8:37     ` Michał Sawicz [this message]

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