[mythtv-users] PXE booting (was Spin up delay for HDDs)

warpme warpme at o2.pl
Thu Sep 29 10:47:09 UTC 2011

>I used to PXE boot but honestly it was more work than it was worth. I
>just switched to a 4gb usb flash disk....I honestly couldn't tell the
>diff between that and pxe. granted im on a 100mb network.

Hmm. I see all arguments for or against PXE are related to NFS variant of PXE.
I agree with them as attribute of this variant is that all communication between execution environment (RAM) and binaries storage is over LAN (sure we have cache but I'm not sure is NFS mounts cached in the same way/efficiency as local mass storage). Effectively it means communication channel with speed of peak 0,7-0,8Gb/s (assuming Gb LAN).

Comparing this to variant with SSD (or any local mass storage) we can say here comm channel has 0,4-1,2Gb/s from platter (HDD) or 1,6Gb/s (assuming 200MB/s SSD) + much faster (6,4 or 12,8G at peak) access to part of binaries from disk buffers cache.

RAM based PXE has all OS/app binaries on RAM disk so here peek comm.speed is about 6,4G/s (DDR2 PC6400 single channel) or 12,8G dual channel.

Comparing all above gives (if RAM is enough big to majority of code in disk buffers cache) hint that local storage might be comparable with RAM PXE (but no faster).
Additionally RAM PXE hasn't additional costs of local storage, it's power consumption and much batter manageability.
No any rocket science here - just classical example of storage hierarchy...

Just my 0.02$

More information about the mythtv-users mailing list