[mythtv-users] network boot / boot speed (WAS: Re: diskless Mythtv USB)

Tim Phipps mythtv-users at phipps-hutton.freeserve.co.uk
Wed Aug 30 18:24:33 UTC 2006

On Monday 28 August 2006 04:19, Drew Bernat wrote:
> On Aug 27, 2006, at 7:23 PM, chris at cpr.homelinux.net wrote:
> > One problem with flash is that it has a limited life-span and will
> > eventually fail if you keep writing to the same area over and over
> > again.  If you were using flash to hold a kernel and an initrd then
> > you'd be OK mounting the root filesystem over the network.  You
> > definitely don't want the root filesystem on flash.

You can mount the root disk as read-only. You'll need to NFS mount some a 
writable directory and put symlinks to it for some files in the root disk so 
it boots OK. A good way to do this is to set up a diskless system and then on 
the server make the diskless root read-only (in /etc/exports). You'll see 
lots of "error read-only filesystem" messages. Once you've fixed them all and 
got the frontend running you can copy the diskless root to the flash disk and 
off you go. Doubtless it will need more tweaking but doing an initial 
diskless setup is much quicker since you can ssh to the server, edit stuff 
and power cycle the client (shutdown is for sissies, pull that power cable 

> I'm using gigabit ethernet, so it's faster than a local disk would
> be. NFS isn't hitting peak bandwidth, but after tweaking (upping the
> read/write size, setting "async") it's plenty good. If you're using
> 100MB you might have problems.

Well, that would be true if the disks on the server were faster than the local 
disks. If the server disks don't rotate faster than the local disks then 
you'll have the same seek time for both plus the network latency for the 
diskless client. Granted the bandwidth you'll see won't be affected by the 
network bandwidth but it's latency that matters when it comes to having a 
snappy frontend.
The option here is to have a local flash disk for the OS, that will always 
beat a diskless setup in terms of latency, and probably bandwidth unless you 
have an insane server.


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