CentOS - Jun 2008 - Software raid tutorial and hardware raid questions.

I remember seeing one with an example migrating
from an old fashioned filesystem on a partition
to a new filesystem on a mirrored lvm logical volume
but one only one side of the mirror is set up at this
time.

First I need to copy stuff from what will become
the second side of the mirror
to filesystem on the first side or the mirror

Then I will be ready to follow the rest of the tutorial
and build and attach the second side of the mirror.

Wish I could remember where I saw that tutorial.

Want to embellish the example and stripe each side
of the mirror.

Understanding  a mirrored pair of stripes,
seems easier than
understanding a striped pair of mirrors.

But this seems like a place where
counterintuitive results are not a big surprise.

I can do mirroring and striping in lvm, mdadm,
or a hardware raid controller.  There are lots of
configurations to ponder.

What about recovery after a hardware raid controller?

What are the chances of being able to replace the controller
and start up successfully from drives?  I know that assuming
the failed controller did write bad stuff to the drives while
it was crashing and burning.

I would not be surprised if the controller firmware revisions
had to match.  I would be surprised but not astonished if
the board hardware revision level had to match, too.
I hope we are past those days.

Anybody know about the
LSI Logic MegaRAID 8480 Storage controller
in particular.


-- 
Drew Einhorn



-- 
Drew Einhorn
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on 6-7-2008 9:35 AM drew einhorn spake the following:
> I remember seeing one with an example migrating
> from an old fashioned filesystem on a partition
> to a new filesystem on a mirrored lvm logical volume
> but one only one side of the mirror is set up at this
> time. 
> 
> First I need to copy stuff from what will become
> the second side of the mirror
> to filesystem on the first side or the mirror
> 
> Then I will be ready to follow the rest of the tutorial
> and build and attach the second side of the mirror.
> 
> Wish I could remember where I saw that tutorial.
> 
> Want to embellish the example and stripe each side
> of the mirror.
> 
> Understanding  a mirrored pair of stripes,
> seems easier than
> understanding a striped pair of mirrors.
> 
> But this seems like a place where
> counterintuitive results are not a big surprise.
> 
> I can do mirroring and striping in lvm, mdadm,
> or a hardware raid controller.  There are lots of
> configurations to ponder.
> 
> What about recovery after a hardware raid controller?
> 
> What are the chances of being able to replace the controller
> and start up successfully from drives?  I know that assuming
> the failed controller did write bad stuff to the drives while
> it was crashing and burning.
> 
> I would not be surprised if the controller firmware revisions
> had to match.  I would be surprised but not astonished if
> the board hardware revision level had to match, too.
> I hope we are past those days.
> 
> Anybody know about the
> LSI Logic MegaRAID 8480 Storage controller
> in particular.
> 
I know that with 3ware controllers, they are always backward compatible, and 
will sell you a controller that will work. As to the "bad" activity,
nothing
will mitigate backups.

-- 
MailScanner is like deodorant...
You hope everybody uses it, and
you notice quickly if they don't!!!!

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