Re: large file system with RAIDframe

[Steven Bellovin <smb%cs.columbia.edu@localhost>]

On Mar 16, 2010, at 5:22 PM, Manuel Bouyer wrote:

> On Tue, Mar 16, 2010 at 01:28:41PM -0400, Steven Bellovin wrote:
>> I'm trying to create a large file system on an amd64/5.x RAID5 system.  The 
>> RAID device in question is not the root partition.  I can't get the 
>> disklabel to say anything sane.
>> 
>> I have three 2TB disks in a RAID5 configuration.  This should, as I 
>> understand things, give me 4TB of usable space.
> 
> I think you're hitting disklabel's on-disk format limitations (32bit 
> integers).
> gpt+wedge is the way to go for such large drives.

I mostly suspect you're right, except that the disk label displayed to me had 
larger numbers than 2^31 -- I just couldn't enter them.

The question, though, is how wedges interact with RAID.  As best I can tell, 
there are no wedges on RAID5 "volumes" -- how are partitions assigned, if not 
via disklabel? 

# dkctl raid1 getwedgeinfo 
dkctl: /dev/rraid1d: getwedgeinfo: Inappropriate ioctl for device

suggests that I can't do it.  (I could, presumably, put wedges on the 
underlying volumes, but those seem to be detected correctly.)

                --Steve Bellovin, http://www.cs.columbia.edu/~smb