[Gluster-users] Netboot / PXE-Boot from glusterfs?

[Benjamin Hudgens]

Here were the notes for us in Debian.  Since these notes are mildly out
of context hopefully they simply give you a starting point.  Rsync is
the tool we use to slurp the debian image.  You manage gluster as you
would on a normal install.  However, you manage the configs and such on
a copy at (X) location which is then slurped into ram on a boot.  For
our dumb storage boxes we dynamically detect drives that need
filesystems, format, then add to gluster configs.  Thus our server
configs get generated on-the-fly.  This allows us to maintain a single
master instance of the OS image and deploy storage boxes quickly.

##############################

Summary:

We want to run a slim install of Debian in ram.  Controlling how we
mount Gluster is simple.  You manage this as you would a regular
install.  Reboot any machine and the changes take effect.  You can blow
away a machine at any time since the OS on our storage machines are
irrelevant and pull from our master copy.

Below remember that ${rootmnt} is pooled from kernel args for the PXE
boot.

Unpackage the initrd:
gzip -dc < ../initrd.img-2.6.30-2-686.netboot | cpio -i

Edit ./init
Modifications start at line 205:

------------
## Make a ramdisk
mkdir /ram
mount -t tmpfs -o size=2G tmpfs /ram

##Move the libraries over since rsync was failing initially.  This just
grabs all the libraries from root
mount ${rootmnt}/lib /lib
mount ${rootmnt}/usr/lib /usr/lib

##Copy the filesystem into ram
${rootmnt}/usr/bin/rsync -rav ${rootmnt}/ /ram/

##Change the rootmnt point to our new location - the rest of the script
will take care of booting us up
rootmnt=/ram
------

Now re-create the initrd image:

find . -print0 | cpio -0 -H newc -ov | gzip -c >
../initrd.img-2.6.30-2-686.netboot

################################




-----Original Message-----
From: gluster-users-bounces at gluster.org
[mailto:gluster-users-bounces at gluster.org] On Behalf Of Jan
Sent: Thursday, June 17, 2010 6:30 AM
To: gluster-users at gluster.org
Subject: Re: [Gluster-users] Netboot / PXE-Boot from glusterfs?

Am 17.06.2010 13:15, schrieb Benjamin Hudgens:
> Hello Jan,
>
> Our company took the approach of slurping our OS into a ram drive and
> then mounting file system points from Gluster.  The OS becomes
> expendable.  In our case (large amounts of dumb storage machines) this
> is okay.  We were itching to get away from NFS.  Boot time is slow
while
> it reads directly from network ->  ram.  However, the final result is
an
> OS that is extremely fast and no NFS dependency.
>
> Obviously this approach is only applicable in certain situations.
>
>    
Hello Benjamin,

Thanks, that's an interesting idea - as long as the root filesystem is 
not too big.
But even then, one might be able to split it up in the most important 
files and directories that are needed to boot and mount the 
glusterfs-directories.
This needs some time to figure out what are the minimum files needed to 
boot until the glusterfs-directories are available - and a minor change 
in the initrd (mount NFS, create ramdisk, copy files). But definitely 
worth a try.

thanks
Jan
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