Re: From TFTP weaknesses to RAMdisk netboot

[C J Considine <conx@connectnet.com>]

Just did 38.5 MB complete in 0:48, 798 kB/s, 64000 byte blocks.

Kent Snook wrote:
> 
> Pricop Ioan wrote:
> >
> > --- Kent Snook <kent.snook@echostar.com> wrote:
> > > We encountered similiar problems. Implemented the
> > > following.
> > >
> > > First results in an automatic reboot upon tftp
> > > timeouts, instead of
> > > waiting for a key press ( we regularly reboot these
> > > hosts remotely ).
> > > Second reduces the tftp timeout to get hosts up and
> > > running much faster.
> > > ( We use ramdisks for all of our diskless hosts, so
> > > images can run up to
> > > 6-10 mb in size, at 5 seconds per packet tftp
> > > timeout, could take 15
> > > minutes or more to boot. Now less than a minute.)
> > >
> > ..........
> > >
> > > --
> > > Kent
> > >
> >
> > Dear Kent,
> >
> > Maybe you can help me with my problem. I am using
> > EtherBoot to experiment with a diskless client. After
> > a few hoops, I made it working from a NFS-root
> > filesystem. Now I am experimenting with RAM-disks. I
> > tried with a 9 MB fs and it seems to work. Then, I
> > tried with a 96 MB fs. Of cause, I modified the
> > /usr/src/linux-2.2.5/drivers/block/rd.c to be able to
> > create ramdisks of 128 MB (have 196 MB on the client)
> > and recompiled the kernel. I tested these, by creating
> > a 128 MB RAMdisk and populating it with the fs I
> > downsized at 96MB. It worked with a "chroot",
> > exception the X part (only fvwm and Netscape). I
> > obtained a 50 MB "rdImage.gz". But when I tried to
> > make a NBI and boot it, all is well until it's
> > tftp-ing the NBI. Than the rotator keeps spinning and
> > spinning forever - i think, cause after 2.5 hours I
> > stopped the process. Anyway, with "tcpdump" I
> > estimated the 3.8 MB composed immage loading time (fs
> > of 9 MB gzipped) and calculated the 51 MB one's - it
> > must have been 1 min and 47 secs. What can be wrong?
> > Can anyone tip me on some sites where I can find
> > specific documentation on NBI use of ramdisks?
> >
> > Thank you for at least reading this mail,
> >
> > =====
> > Ioan (John) NIKY Pricop
> > Bucharest - ROMANIA
> > pniky@yahoo.com
> >
> 
> A 96MB image could take many hours to tftp to the client. Before I
> changed the TFTP_TIMEOUT value, a 10MB image could take 30 minutes on a
> GOOD day. Turn on block counting with etherboot to get a visual of which
> block you are on. If you require a filesystem as large as you are trying
> to load, I would recommend using nfs instead of a RAMDISK. We took the
> RAMDISK route to free our diskless hosts from dependencies on other
> hosts on our net.
> 
> We use make to run a Makefile which in turn executes shell commands and
> calls shell scripts to create our images. Our largest image/filesystem
> is around 10mB. I would recommend creating a filesystem that contains
> only the binaries you actually require. Use ldd to determine the
> libraries you need and eliminate the ones you don't need. Strip all
> files (be carefull with any modules- don't use the --strip-all option
> for these!!).
> 
> Hope this helps.
> 
> --
> Kent
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C J Considine <conx@connectnet.com>
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