-----Original Message-----
From: NeilBrown [mailto:neilb@suse.de]
Sent: Monday, December 05, 2011 12:01 AM
To: Leslie Rhorer
Cc: linux-raid@vger.kernel.org
Subject: Re: Is this stupid?

On Sun, 4 Dec 2011 16:28:25 -0600 "Leslie Rhorer" [off-list ref]
wrote:

quoted

I have a system - one that is not expandable - that has relatively

limited

quoted

RAM, comparatively speaking, and must boot from a usb stick.  The system
hosts a RAID array, but one cannot assume the RAID array is available

when

quoted

the system boots.  IOW, I want to be able to take down the RAID array

for

quoted

maintenance, possibly booting the system with no array created, at all.

On the other hand, USB sticks have a limited number of writes available
before they fail, so I don't want the system to be thrashing the flash

drive

quoted

any more than necessary.  At this time,  I have /var/run, /var/log,
/var/lock, and /tmp mounted as tmpfs file systems.  What I propose is to

run

quoted

an init script that checks to see if the array is mounted, and if so

appends

quoted

files in the aforementioned directories to existing directories on the

array

quoted

and then remounts and binds the directories on the array.  The stop call

in

quoted

the script will reverse the process so the system can shutdown or so I

can

quoted

take the array offline after booting for maintenance.  Is this unwise?

Am I

quoted

missing something crucial that might cause the system to blow up?

Sounds reasonably sane.

After the bind mount you would need to make sure any process with a file
open in one of those directories re-opens the file.  So you might want to
restart syslogd.

Yeah, I was intending to do that, along with any other processes that
require it.  'Basically do the same thing that logrotate does.