Trials and tribulations on mirroring....
noackjr at alumni.rice.edu
Tue Jan 18 22:11:35 PST 2005
On 01/18/05 23:46, Karl Denninger wrote:
> <snip backstory and gvinum stuff>
> So, my next attempt (with a new, fresh load) was to give gmirror a shot
> instead, since I only need Raid 1, and this looks like a "better" option
> from that perspective given gvinum's squirrely and not-all-there status at
> the moment.
> Weeeeellll.. the manual page (and the archives on the list here) implies that
> I can do the following:
> 1. Set up the system on one of the two mirror disks.
> 2. In single user mode, use "gmirror label -v -b round-robin disk ad4"
> to set up the pre-existing disk (with data on it), which I booted from,
> as the "primary".
> 3. Then use "gmirror insert disk ad6" to add the secondary (mirrored) disk,
> which will automatically sync it and bring them into a consistent state.
> Only one small problem - the first command (in #2) fails, with:
> "Can't store metadata on ad4: Operation not permitted"
> This is true if the system is mounted read-only (in single user mode) or
> read-write (in multiuser, with all filesystems mounted)
> Attempting to label the SECOND (bare) disk works, but of course that's
> backwards and an "insert" would immediately destroy the running system (I
> assume it would also fail with the same permission error, but I've not tried
> it) - so that's not an option.
> I also tried it from the fixit disk, but the KLD cannot be loaded from the
> fixit disk, and none of the commands work - so that appears to not be an
> option either.
> How do you get this thing set up? The archives here (and man pages)
> strongly imply that this works for a root filesystem and boot drive -
> what am I missing?
> Need a Raid 1 solution that works to move over to the 5.x world out here...
If any filesystem is mounted then GEOM will not allow metadata updates
for the drive. Here's a solution given over on the geom@ list:
I converted to gmirror from ataraid, so I already had 2 disks with
identical contents. I worked around this problem as outlined here (the
instructions have errors that are corrected later in the thread):
I wish we handled this in the installer, but as I can't produce the code
to do it I'll shut up now...
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