van Sleeuwen, Berry wrote:
Mark,
Hm, I even didn't think about cache and what it could do to not only
files but also to the filesystem itself. And even if I did I'd have
guessed it would only mess up a logfile that isn't in use on the target
anyway. We would start in a new machine with an empty /var/log/messages
and /var/log/warn for example.
I think I'll start on a new machine to be used for resque and cloning so
that we must run our cloning from a separate machine.
Thanks, Berry.
-----Original Message-----
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of
Mark Perry
Sent: donderdag 21 augustus 2008 13:27
To: [email protected]
Subject: Re: Root filesystem error switches to ReadOnly
van Sleeuwen, Berry wrote:
Hello Mark,
I'll have to look into the flashcopy process but have not taken the
time for it just yet.
I guess one thing that would be wrong then is that I copy from the
live system. So the source nlzlx920 is being copied from within the
nlzlx920. But would that introduce IO errors on the target disks? If
anything I'd expect to see errors during boot of the target guest.
Either in a filesystemcheck or dmesg afterwards. Much like when you DDR
a live VM and get a warmstartdata error when the target is IPLled.
Perhaps a rethink of the process is in order. I guess a resque system
would be an option. I do like to have a resque machine so I could also
use that machine to do the cloning.
As for other questions, I also assume I have the rights. No errors on
that part. Same amount of cylinders. I have not yet ran the fsck on the
source nor did I test it in a failsafe IPL of a new target. I dd with
"dd bs=4096 if=$sDev of=$tDev" no other options. Haven't ran dd during
the process by hand, other than a manual test to clone the first machine
and to test the steps in the script. No erep or errors within the
operator log. There is no error from the VM part. It's only within the
linux.
Regards, Berry.
I don't recommend it for normal use, but I have cloned a running Linux
system, without mounting its filesystems ro.
I did it over a network, and used a procedure like this:
1. Partition target drive
2. mke2fs as needed.
3. mkdir and mount to get the volume structure right.
4. ssh [EMAIL PROTECTED] tar clC /boot / var (whatever) | tar xpC /mnt/dest
Now this carries the risk of having some corrupted files - log files,
and application data such as your databases and email, unless you shut
them down. In my case, that was unimportant.
You can safely clone the running system as you did, provided that any
mounted relevant filesystems, including /, are mounted ro. Generally,
this implies booting to single-user mode.
Running fsck after the cloning process will show you it's okay.
Never clone a "live" Linux filesystem. Once the filesystem has been
mounted the filesystem is cached in storage (as are updates) and the on
disk filesystem is marked 'dirty".
Stop the "master" linux system with a clean shutdown, and copy the disk
using flashcopy or ddr if you prefer.
This new copy is the "master" disk to be used for future copies.
Reboot the Linux system and run an e2fsck on the new copy to ensure it
is good. Then clone as you like ;-)
--
Cheers
John
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