Subject: Re: disklabeling a 5 TB partition!?
To: Christos Zoulas <email@example.com>
From: Brian Buhrow <firstname.lastname@example.org>
Date: 08/04/2006 11:37:02
In April I started a thread on this list with the subject:
Large disk support ...
The take aways from that are as follows:
1. Disk labels in NetBSD and FreeBSD do not support logical disks larger
than 2^32 sectors, which is just over 2TB with 512 byte sectors.
2. If you run a filesystem on a raid 5 system using the raw partition, you
might or might not be able to get more space, but if you do that, you
won't be able to do things like recalculate parity while the filesystem is
mounted. Given the time it takes to calculate parity on something that
large, this is probably a trade off you're not going to want to make. At
least, I wasn't willing to make it.
3. The answer is that global partitioning should be implemented, with
wedges and legacy disklabels installed on top of the global partitions.
This work is not done under NetBSD or FreeBSD, but some of it is done, and it
needs to be pulled together and integrated into the system.
4. I looked, but couldn't be sure, and thought there might be some sign
bit issues related to some of the code in raidframe with respect to its
manufacturing of fictitious disklabels. I don't know if those issues
extend into the raidframe mechanism itself.
The fact that this issue is coming up more and more often, probably
means some work needs to be undertaken to allow NetBSD to play with these
new larger storage facilities.