Mark Allums wrote:
elijah rutschman wrote:
On Mon, Oct 27, 2008 at 12:37 PM, Freddy Freeloader
<[EMAIL PROTECTED]> wrote:
Just out of curiosity, will the ability to create RAID10 arrays ever be
integrated into the installer?
Oh, and while I'm at it, how about raid1 arrays with more than 2
drives? I
did a Lenny install today and could not create a 1.2 terrabyte
mirror with 4
640 gig drives. I was limited to 2 640 gig arrays of two drives
each at
best. If I told the installer I wanted all 4 drives in a mirror it
gave me
1 640 gig mirror and reported the array used all 4 drives.
Hello,
AFAIK, RAID1 doesn't do any striping, so no matter how many disks you
include in your array, you have a maximum usable device size equal to
the smallest disk in the array. In your case, your maximum disk size
would be 640gigs.
It sounds like you want to do something like RAID5; you'd have some of
the benefits of striping and some of the benefits of mirroring. I've
only ever setup a RAID1 array with Debian, and I don't remember what
options were presented during installation. You might be able to
replicate RAID5 using LVM + RAID1 if RAID5 is not an explicit
installation option. I have yet to experiment with LVM, so I don't
know what this would entail, but I'm sure other members of this list
could be more helpful in this area.
Regards,
Elijah
No, he wants to do a 10, or 1+0 RAID. Mirror two pairs of drives,
then stripe across the pairs. This is a compromise when a RAID 5
isn't quite practical for some reason. RAID 5 can be slow on a
software setup when the partition is large and it fills up significantly.
Mark Allums
Hmmm.... I just figured that it would be possible for mdadm to be smart
enough to realize that if you gave it 4 drives in a mirror it would at
least take two of them for each portion of the mirror without having to
stripe them. I just assumed that if Linux raid is smart enough to
automatically integrate hot spares upon drive failure then it could
figure out how to use 4 drives to create a larger mirror. Guess that's
what I get for assuming.
What I really wanted was to create a RAID10 array during the install and
was playing around trying to see if I could work out another solution
during the install even if it would be a little slower. Anyway, I
created the array after the install was finished. I just wasn't aware
of the 2 drive RAID1 limit in my experimentation. Nothing I had read
on Linux raid mentioned this limit.
Yeah, the man page examples for RAID1 use only 2 drives, but normally
examples in man pages are usually very simple and don't cover all
possibilities. Usually they're just there to give you an example of
the syntax and switch usage.
Anyone know if/when RAID10 capability will be included in the installer?
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