On Mon, Dec 22, 2014 at 12:02 PM, Michael Torrie <[email protected]> wrote:
> Well I don't think netbooting will be quite as fast as local SSD. But > it might be fast enough. The Linux Terminal Server project has been > doing this sort of thing for years. Seems to have worked out fine. > They might have more information that would be of value to you. > http://www.ltsp.org/ > > I also came across an article a couple of years ago of a guy who not > only did this with Linux, but also netbooted diskless Windows 7 > machines. I think he used software iSCSI for the Windows main volumes. Most likely not as fast as a local SSD, but I would bet that the boot speed depends greatly on the method of network booting. The tftp protocol, which is the "standard" method of network booting Linux, is horrifically slow. It transfers files in 512 byte blocks (encapsulated in UDP/IP framing) and the sender waits for positive acknowledgement from the receiver before sending the next datagram. Your kernel and initial ramdisk are typically downloaded this way, and it's going to be *way* less efficient than reading from any drive. You may be able to tweak your boot client and tftp server to allow larger block sizes, but this is still hugely less efficient than booting from a local disk. This is only a small part of a typical Linux system's boot time (just getting through all the BIOS crap probably is the longest bit on a server-class motherboard, unless they've changed greatly in the last few years) but seems to contribute quite a bit of "feeling slow" if you're just watching it. Booting directly via iSCSI (assuming your network card supports this) is likely to make *far* more efficient use of the network than tftp booting will, so it's likely to feel a lot less delayed than a typical network boot will, and those aren't even terribly painful, especially if you don't reboot a lot. I'm not experienced enough with iSCSI to say how its performance will compare to NFS, but it probably depends on how much offloading your network hardware is doing for you. Regardless, NFS is no doubt far more efficient than tftp, so once you've got the root filesystem mounted the difference between a local disk and remote filesystem will be less dramatic than for the initial kernel and ramdisk load. Anyway, make what you will of that bit of rambling. YMMV. --Levi /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
