Re: switching bsdlabel's label

2009-01-21 Thread Patrick Tracanelli

Jerry McAllister escreveu:

On Wed, Jan 21, 2009 at 10:45:28AM -0200, Eduardo Meyer wrote:


On Tue, Jan 20, 2009 at 4:42 PM, Jerry McAllister  wrote:

On Tue, Jan 20, 2009 at 03:36:34PM -0200, Eduardo Meyer wrote:


On Tue, Jan 20, 2009 at 2:13 PM, Patrick M. Hausen  wrote:

Hello,

On Tue, Jan 20, 2009 at 01:24:27PM -0200, Eduardo Meyer wrote:

I have a certain disk where da0s1a and da0s1d are inverted. By some
reason someone labelled root as 'd' and home as 'a'.

Can I just

bsdlabel -n da0s1 > savedabel.txt

Edit savedlabel.txt, switch and restore? (bsdlabel -R da0s1 savedlabel)

Why not simply use bsdlabel -e da0s1?

Because I didnt know about that? ;-)

Thank you for the hint.

However I still have the same doubt. Since basically its the same
task, Is it safe do relabel this way?

Hmmm.  Is there stuff written on the disk.  Is root stuff really written
on da0s1d and /home stuff really written on da0s1a?   Does the system boot
from it OK?

Or is it just that the mounts are switched.
The mount points are not written in to the label.   That comes after
booting.   If it boots, I wonder if it really is switched on the
partitions or if it is just that the partitions are mounted backwards
(probably due to editing /etc/fstab incorrectly).

jerry

Hello Patrick, thanks again. Yes, label is switched. Yes there really
are stuff on the partitions. No, I dont boot from da0s1d. It is a disk
for migration. But the one who partitioned was fooled by Sysinstall
which creates the first label on extra disks as 'd' and the last from
the allowed 7 as 'a'. Therefore this server is still booting on the
original disk (ad6s1a) and everything else is mounted in the new one
(da0s1), everything but root.


What sysinstall does is assume that the 'a' partition will be
used for a root mount and the 'b' partition will be used for swap.
Sinc 'c' is reserved, it starts with 'd'.   Then, if you later 
add an 'a' it will end up being later (higher offset) than the 'd'.


I suppose it might confuse a person, but otherwise it is no problem
and probably would be best to just leave it that way.   You really
only need to use the mount point anyway most of the time.  So, if
the mount point addresses the partition you want to with that name,
then you should have no problem.

You could switch it around using bsdlabel, but I don't think the 
risk would be worth the negligible gain.   But, do as you wish.


jerry 








Kind regards,
Patrick
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Hello,

Yes, you can do this change anytime you want, since (1) da0s1* are 
unmounted and (2) disk is clean. Therefore I suggest you are in single 
user mode. If you feel unsure, backup the current label scheme with


disklabel da0s1 -n > da0s1.disklabel.bk

You can restore anytime with the Rescue Disk.

Go ahead, no problem.

Sometimes you will really have problem booting from a disk if root is 
not on label 'a'. I believe it can be workarounded, but your will is 
safe, go ahead and switch the labels.


You can always remember the person who did this from sysinstall that 
sysinstall will label as 'a' if the mount point is root (/).


Therefore if someone wants to use sysinstall for labelling in 
production, and wont mount on / since / has the current root, one can 
always fool sysinstall, (C)reating the partition, using / as mpoint and 
mater redefining the (M)ount point to somewhere else, say, to /mnt.


I always relabel this way, never had a problem. TinyBSD sometimes 
relabels this way too, for some PC Engines Wrap boards. Go ahead.


--
Patrick Tracanelli

Tel.: (31) 3516-0800
316...@sip.freebsdbrasil.com.br
http://www.freebsdbrasil.com.br
"Long live Hanin Elias, Kim Deal!"

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failover+balancing options

2007-08-01 Thread Patrick Tracanelli
Hello,

I have a problem and could not find a solution yet. I would like to
hear you opinion.

I have 2 machines, machine A and machine B. They are mail servers
serving with Maildir. I need to find out a solution where I can do
balancing between server A and B while in production, and, if one of
the nodes get down, only the other one will do the work of both.

The main problem I find is a solution regarding the information (data
stored). Right now I have it running with NFS on a third machine,
machine C for example. I know machine C is a SPOF but it is
acceptable.

The big problem is performance. NFS is going away on huge load.

I did ggate0+local disc RAID 1 with gmirror. Sincronization on writing
works perfectly but I can not mount the same disk locally while
exporting it via ggated. Why cant I mount it? Anyone knows? If I
could, eliminating the SPOF would be very easy. Performance would be
great too because ggated performance is way better than NFS on this
kind of operations, specially because READ operations can be done on a
local disk (priority configured via gmirror).

Any idea on how to setup this enviroment?
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