* Re: second controller: what will my discs be called, and does it matter?
2006-07-06 18:12 second controller: what will my discs be called, and does it matter? Dexter Filmore
@ 2006-07-06 22:05 ` John Stoffel
2006-07-06 22:20 ` Neil Brown
` (2 subsequent siblings)
3 siblings, 0 replies; 6+ messages in thread
From: John Stoffel @ 2006-07-06 22:05 UTC (permalink / raw)
To: Dexter Filmore; +Cc: linux-raid
Dexter> Currently I have 4 discs on a 4 channel sata controller which
Dexter> does its job quite well for 20 bucks. Now, if I wanted to
Dexter> grow the array I'd probably go for another one of these.
So, which SATA controller are you using? I'm thinking my next box
will go SATA, but I'm still deciding....
Dexter> How can I tell if the discs on the new controller will become
Dexter> sd[e-h] or if they'll be the new a-d and push the existing
Dexter> ones back?
Dexter> Next question: assembling by UUID, does that matter at all?
Dexter> (And while talking UUID - can I safely migrate to a
Dexter> udev-kernel? Someone on this list recently ran into trouble
Dexter> because of such an issue.)
I'm using udev and it's not a problem, but I admit I'm also
auto-assembling my arrays using the kernel detection stuff. All I
have in my mdadm.conf file is
MAILADDR john
PARTITIONS
and it just works for me. But using the UUID is the way to go.
Though I admit my system may not be setup like you think. I have a
pair of 120gb drives which are mirrored. On top of them I have LVM
configured and a pair of partitions setup, so I can grow/move/shrink
them at some point. Hasn't happened too often yet.
So I'm not using ext3 -> MD -> disks, I'm adding in the LVM layer.
John
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: second controller: what will my discs be called, and does it matter?
2006-07-06 18:12 second controller: what will my discs be called, and does it matter? Dexter Filmore
2006-07-06 22:05 ` John Stoffel
@ 2006-07-06 22:20 ` Neil Brown
2006-07-07 13:15 ` Gabor Gombas
2006-07-17 18:28 ` Bill Davidsen
3 siblings, 0 replies; 6+ messages in thread
From: Neil Brown @ 2006-07-06 22:20 UTC (permalink / raw)
To: Dexter Filmore; +Cc: linux-raid
On Thursday July 6, Dexter.Filmore@gmx.de wrote:
> Currently I have 4 discs on a 4 channel sata controller which does its job
> quite well for 20 bucks.
> Now, if I wanted to grow the array I'd probably go for another one of these.
>
> How can I tell if the discs on the new controller will become sd[e-h] or if
> they'll be the new a-d and push the existing ones back?
No idea. Probably depends on where you plug it in, but also on the
phase of the moon :-)
>
> Next question: assembling by UUID, does that matter at all?
No.
> (And while talking UUID - can I safely migrate to a udev-kernel? Someone on
> this list recently ran into trouble because of such an issue.)
Depends on what you mean by 'safely'.
If you mean "can I change something that fundamental and expect
everything will just work perfectly without me having to think" , then
"no".
If you mean "should it be fairly easy to fix anything that breaks, and
can I be confident that my data will be safe even if something does
break", then "yes".
NeilBrown
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: second controller: what will my discs be called, and does it matter?
2006-07-06 18:12 second controller: what will my discs be called, and does it matter? Dexter Filmore
2006-07-06 22:05 ` John Stoffel
2006-07-06 22:20 ` Neil Brown
@ 2006-07-07 13:15 ` Gabor Gombas
2006-07-17 18:28 ` Bill Davidsen
3 siblings, 0 replies; 6+ messages in thread
From: Gabor Gombas @ 2006-07-07 13:15 UTC (permalink / raw)
To: Dexter Filmore; +Cc: linux-raid
On Thu, Jul 06, 2006 at 08:12:14PM +0200, Dexter Filmore wrote:
> How can I tell if the discs on the new controller will become sd[e-h] or if
> they'll be the new a-d and push the existing ones back?
If they are the same type (or more precisely, if they use the same
driver), then their order on the PCI bus will decide. Otherwise, if you
are using modules, then the order you load the drivers will decide. If
the drivers are built into the kernel, then their link order will
decide.
Gabor
--
---------------------------------------------------------
MTA SZTAKI Computer and Automation Research Institute
Hungarian Academy of Sciences
---------------------------------------------------------
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: second controller: what will my discs be called, and does it matter?
2006-07-06 18:12 second controller: what will my discs be called, and does it matter? Dexter Filmore
` (2 preceding siblings ...)
2006-07-07 13:15 ` Gabor Gombas
@ 2006-07-17 18:28 ` Bill Davidsen
2006-07-17 21:45 ` Dexter Filmore
3 siblings, 1 reply; 6+ messages in thread
From: Bill Davidsen @ 2006-07-17 18:28 UTC (permalink / raw)
To: Dexter Filmore; +Cc: linux-raid
Dexter Filmore wrote:
>Currently I have 4 discs on a 4 channel sata controller which does its job
>quite well for 20 bucks.
>Now, if I wanted to grow the array I'd probably go for another one of these.
>
>How can I tell if the discs on the new controller will become sd[e-h] or if
>they'll be the new a-d and push the existing ones back?
>
>
For software RAID you shouldn't care, for other things you might.
>Next question: assembling by UUID, does that matter at all?
>
>
No. There's the beauty of it.
>(And while talking UUID - can I safely migrate to a udev-kernel? Someone on
>this list recently ran into trouble because of such an issue.)
>
You shouldn't lose data unless you panic at the first learning
experience and do something without thinking of the results. I would
convert to UUID first, obviously.
--
bill davidsen <davidsen@tmr.com>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: second controller: what will my discs be called, and does it matter?
2006-07-17 18:28 ` Bill Davidsen
@ 2006-07-17 21:45 ` Dexter Filmore
0 siblings, 0 replies; 6+ messages in thread
From: Dexter Filmore @ 2006-07-17 21:45 UTC (permalink / raw)
To: Bill Davidsen; +Cc: linux-raid
Am Montag, 17. Juli 2006 20:28 schrieb Bill Davidsen:
> >Next question: assembling by UUID, does that matter at all?
>
> No. There's the beauty of it.
That's what I needed to hear.
>
> >(And while talking UUID - can I safely migrate to a udev-kernel? Someone
> > on this list recently ran into trouble because of such an issue.)
>
> You shouldn't lose data unless you panic at the first learning
> experience and do something without thinking of the results. I would
> convert to UUID first, obviously.
Already happened. Biggest problem so far is coming up with a sane backup
solution for 500gigs of data :P
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^ permalink raw reply [flat|nested] 6+ messages in thread