[mythtv-users] Need advice for storage project

[Maarten]

On Thursday 22 July 2004 12:29, PAUL WILLIAMSON wrote:
> >>> mythtv at ultratux.org 07/22/04 5:57 AM >>>


> LVM is your friend in this case.  You can add a single hard disk, slowly
> (or quickly)
> migrate the data off an older smaller drive to the newer, bigger, faster
> drive,
> resize the volume and remove the old device, then physically remove the
> drive.  Wash, Rinse, Repeat.  Piece of cake.  The only pain to go
> through
> is actually getting LVM set up and running in the first place, but once
> done, you'll
> never have to worry about adding or removing drives again.

Well, I've heard that story numerous times but it has always left me with one 
important issue.  But more on that below.  First, the reason I want to avoid 
adding any disks to the current server is that it get too crowded.  As it is, 
it already has 3 ATA promise cards.  Adding additional SATA promise cards + 
drives is not only awkward due to place restrictions and PSU issues, it can 
also trigger renumbering of the installed drives. Now I'm perfectly capable 
of checking whether the drive I plan to format is a 80 GB one or a bigger 
one, but it still opens up numerous possibilities for human error.
Secondly, I cannot add single drives; I have to define the raid 5 array with 
all drives online, otherwise it cannot be started at all.

Then I get to the LVM part.  What always puzzled me is what that brings me. 
Sure, with LVM one can resize the underlying disk, but the partition on top 
of that doesn't get resized.  So I have to resize my reiserfs.  Not only do I 
not trust resizing very much, it too can be error prone.
Besides, adding a new logical volume of xxxGB to an LVM set and removing the 
old volume is akin to just have both volumes started and copy it all over in 
the usual way, isn't it ?  
Since I do not plan to use the older drives any longer than neccessary 
-they're getting flaky according to S.M.A.R.T- I see no reason to deploy LVM.
If someone tells me they've resized reiserfs partitions 20 times without 
losing data a single time, then I might reconsider, but for now it is too 
much unfamiliar territory for me to test that out on my valueable data. 
You see, backups are indeed neccessary etc etc but how can you be confident 
you have a full, working backup of a 400GB array ?  I do not have 100 DVD-RWs 
laying here with something like a complete, up-to-date backup. So I have to 
be 'real careful'.
Not to mention smarter than that irritating meddling guy Murphy who always 
sticks his nose into business that shouldn't concern him.  ;-\

Maarten

-- 
Linux: Because rebooting is for adding hardware.