[mythtv-users] Diskless

Andrew Wilson migmog at gmail.com
Tue Jan 30 23:58:20 UTC 2007

I run a diskless frontend on an epia m10k with 512MB RAM. It works
just fine. Root filesystem is on the network. The server is a low
power Maxtor Shared Storage - similar in concept to Linksys NSLU2. It
boots the frontend using the excellent dnsmasq server for dhcp and
hpa-tftpd for tftpboot - took a while to get this going, but now it is
flawless. The frontend power button is ACPI'd to suspend to RAM, so it
'boots' in about 5s unless I need to power off. Frontend draws about
3W when suspended - which is about the same as when it is OFF but
still connected to the PSU... Shocking!

The backend is a cheap (20!) compaq small form factor office pc which
lives in a cupboard. It has 256MB RAM a pair of (cheap) DVB-T cards,
and a small disk for OS and swap, though I've not needed the swap and
I could probably boot this over network as well. Recordings are stored
on a NFS mount on the MSS.

The Maxtor box runs cool, draws about 7W and is on 24/7. It also has
the task of waking the backend when a recording is imminent. The
backend draws about 25W when on, and the frontend draws about 30W. I
also have a belkin wireless adsl router which draws about 17W. In
theory the MSS could do this job as well, but to be honest I've not
tried, and I don't really have time.

Everything works OK. The network is wired 100 base tx, not even close
to being saturated. When HD-DVB comes along I'll probably need to
upgrade the frontend, but hey I'll need to upgrade my TV first! The
network should still be OK, and the backend should be fine as all it's
doing is copying a still fairly low bitrate data stream from a PCI
card to Ethernet.

One problem I have is that it seems to be impossible to do wake on lan
from suspended (S3) on the backend, probably due to 20th century
hardware. So the backend does a normal shutdown when it's idle.Still
it boots up mysqld and mythbackend in about 30s which isn't bad. It's
just a shame that the frontend is ready before it.

What would be REALLY nice is to run a kind of boss backend on the MSS
which knows nothing about recording TV, but can serve mythweb and
recordings to the frontend on demand. Then I would not have to wait
for the real backend to wake up. This should surely be possible in
32MB RAM, though maybe a full MySQL database is too heavy for this
task. Perhaps I could do some sort UPnP thing for this, and not bother
with a myth frontend. I do all scheduling though Mythweb anyway, and
the frontend is only used for viewing recodings.

Hope this helps you see what's possible,.....


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