Am 19.02.2013 18:19, schrieb Ian Malone:
On 17 February 2013 21:12, Reindl Harald
<h.reindl(a)thelounge.net> wrote:
>
>
> Am 17.02.2013 22:03, schrieb Heinz Diehl:
>> On 17.02.2013, Reindl Harald wrote:
>>
>>> if wouldn't do this and stick with dd / disk images and use gparted
>>> to resize partitions because if i clone machines i want to have
>>> all UUID's the same
>>
>> You can easily change/tailor your UUIDs with tools like tune2fs
>
> have fun change also the RAID UUID's everywhere
> and setup all identical because you have also
> internal UUIDs on the RAID-partitions
>
>
> [root@srv-rhsoft:~]$ cat /etc/mdadm.conf
> MAILADDR root
> AUTO +imsm +1.x -all
> ARRAY /dev/md0 level=raid1 num-devices=4 UUID=1d691642:baed26df:1d197496:4fb00ff8
> ARRAY /dev/md1 level=raid10 num-devices=4 UUID=b7475879:c95d9a47:c5043c02:0c5ae720
> ARRAY /dev/md2 level=raid10 num-devices=4 UUID=ea253255:cb915401:f32794ad:ce0fe396
>
> oh yeah and the tun2fs-output of /dev/md0 is
> [root@srv-rhsoft:~]$ tune2fs -l /dev/md0 | grep UUID
> Filesystem UUID: 1de836e4-e97c-43ee-b65c-400b0c29d3aa
>
> again: have fun to reacreate this setup 1:1 after rsync to
> new drives - i bet it would not work at the end - well it
> may not interest you on your setups, mine are always two
> identical machines which are synced daily
>
>> The "dd" approach has a bunch of disadvantages, one of the biggest is
>> misalignment if your new drive is a SSD or advanced format HDD
>
> which misalignment?
>
> if i switch to SSD some years later as soon as 4x2 TB are at a
> normal price i will simply remove disk 1, insert a SSD, rebuild
> RAID and after the rbuild the same for the other 3 drives
>
>
I don't have a solid reference for this, only hearsay, but dd as a way
to transfer filesystems or partitions to SSD probably interferes with
wear-levelling.
http://serverfault.com/questions/282555/zeroing-ssd-drives
http://www.wonkity.com/~wblock/docs/html/ssd.html
I guess RAID tools must now have some way to address this
that is why i said "if 2 TB SSD's are at a normal price" which
will not happen now AND not until i trust them which is not
the case now and at least a disk have to survive running
full without damage/impact for call it trustable
the SD-card of my HTC hero destroyed the whole phone with
overheat and the root cause was that it no longer did write
any data but confirmed "all OK", i tried to put the SD-card
on my PC, formatted it with different filesystems, did
overwrite it with zero as also with random crap and each
time after i took it out of the reader and inserted it
again the last written data days ago where untouched
NOTICE: and not a single warning in "dmesg" or /var/log/messages
the whole time while any spinning disk would lead to warnings
or errors in such cases - you understand while i do not trust
them currently