On May 5, 2007, at 09:34, Mario Goebbels wrote:
I spend yesterday all day evading my data of one of the Windows
disks, so that I can add it to the pool. Using mount-ntfs, it's a
pain due to its slowness. But once I finished, I thought "Cool,
let's do it". So I added the disk using the zero slice notation
(c0d0s0), as suggested for performance reasons. I checked the pool
status and noticed however that the pool size didn't raise.
After a short panic (myself, not the kernel), I remembered that I
partitioned this disk as EFI disk in Windows (mostly just because).
c0d0s0 was the emergency, boot or whatever partition automatically
created according to the recommended EFI partitioning scheme. So it
added the minimal space of that partition to the pool. The real
whole disk partition was c0d0s1. Since there's no device removal in
ZFS yet, I had to replace slice 0 with slice 1 since destroying the
pool was out of the question.
Two things now:
a) ZFS would have added EFI labels anyway. Will ZFS figure things
out for itself, or did I lose write cache control because I didn't
explicitely specify s0 though this is an EFI disk already?
yes if add the whole device to the pool .. that is use c0t0d0 instead
of c0t0d0s0 .. in this case, ZFS creates a large partition on s0
starting at sector 34 and encompassing the entire disk. If you need
to check the write_cache use "format -e", cache, write_cache, display.
b) I don't remember it mentioned anywhere in the documentation. If
a) is indeed an issue, it should be mentioned that you have to
unlabel EFI disks before adding.
Removing an EFI label is a little trickier .. you can replace the EFI
label with an SMI label if it's below 1TB (format -e then l) and then
"dd if=/dev/zero of=/dev/dsk/c0t0d0s2 bs=512 count=1" to remove the
SMI label .. or you could also attempt to access the entire disk
(c0t0d0) with dd and zero out the first 17KB and the last 8MB, but
you'd have to get the 8MB offset from the VTOC. You know you've got
an empty label if you get stderr entries at the top of the format
output, or syslog messages around "corrupt label - bad magic number"
Jonathan
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