RAID-5 expansion / harddisk replacement (with bigger disks) withouttotal data-loss

Michael Weber mweber at alliednational.com
Tue Aug 19 08:09:00 CDT 2003


Greetings, Nicolai.

I don't think you will have the kind of success you are planning on
with this scenerio.  From what you describe, you seem to be wanting to
migrate with zero down time.  It just isn't going to happen.  Even if
you do manage to migrate from 9 GB drives to 36 GB ones, you will still
be left with 9GB containers.  If you use AFA to change the container
size, you'll still be left with 9GB partitions.

I recommend getting a good tape backup, removing the 9GB drives,
install and configure and partition the 36GB drive aray and restore from
tape.  Far fewer questions, risks, etc.  If you have enough slots, you
can leave the 9 GB drives in and do a disk to disk copy (use cp not dd!)
rather than a tape restore for less down time.

And you have a fall-back ready to go should you need it.  Just put the
9GB drives back in and hit the power switch.

My $0.02.

>>> Nicolai Schleifer <schleifer at chamaeleon.de> 08/19/03 05:49AM >>>
Hello,

I'd like to replace the four 9GB harddisks of container 1 in the
example
below against 36GB harddisks without having a total data loss of that
container. The goal is to extend the overall size of that container
from "(4 time 9GB)-raid-5_overhead" to "(4 times
36GB)-raid-5_overhead".

I think it should be possible, by first replacing all the 9GB
harddisks,
one by one (like if they were broken and needed to be replaced) and
after that by extending the container's size to the full extent that
should be possible by then (found hints about that, using afacli
commands "container reconfigure"/"container extend").

I'm currently reading this mailinglist about my planned expansion
task,
to various different results. I can't find an example on the list
which
matches my task. Any hints?

Example Configuration:
AFA0> container list
Executing: container list
Num          Total  Oth Chunk          Scsi   Partition
Label Type   Size   Ctr Size   Usage   B:ID:L Offset:Size
----- ------ ------ --- ------ ------- ------ -------------
 0    Mirror 8.47GB            Open    0:00:0 64.0KB:8.47GB 
 /dev/sda             SYSTEM           0:01:0 64.0KB:8.47GB 

 1    RAID-5 25.4GB       64KB Open    0:02:0 64.0KB:8.47GB 
 /dev/sdb             DATA             0:03:0 64.0KB:8.47GB 
                                       0:04:0 64.0KB:8.47GB 
                                       0:05:0 64.0KB:8.47GB 

Maybe someone can tell me if it's possible at all. A recipe on how to
do it would even be greater.

Thank you! :)


Greetings Nicolai
-- 
Nicolai Schleifer
Chamaeleon Aktiengesellschaft
fur innovative Netzlosungen
Robert-Bosch-Str. 12 / Haus IV
D-56410 Montabaur
Hotline:  +49 26 02 - 10 16 9 - 160
Zentrale: +49 26 02 - 10 16 9 - 0
Fax:      +49 26 02 - 10 16 9 - 101
Funk:     +49 177 - 32 08 60 7
Email: schleifer at chamaeleon.de 
http://www.chamaeleon.de 

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