TFTP Load Balancing?

[Robin Abecasis]

We have over 20 TFTP servers (HPUX 10.20) and over 4500 XTerminal thin clients (Enware & Enware2 HP devices). I am interested in hopefully finding a load balancing solution so that we can load balance the TFTP servers (and thus the TFTP IP protocol). Has anyone done this before, had experience with this, know of any products/solutions to help me. Please? :)

Cheers,
Robin

[Bill McNAMARA_1]

Use different Boot Servers for the Xterms.
Remeber most of the Xterminals traffic is X protocol, so you should ideally have multiple application servers. The application is the one generating the traffic to the Xterm.
You can modify the Xserver under F12 or remote config to XDMCP to different hosts, but can boot all from the same server.. thus moving X traffic onto different servers.

Otherwise you want to use some type of intelligent switch between you Xterm and boot/X host. Maybe a procurve?

Try also to get your hands on the Xterms 100BaseT card rather than using the onboard 10BaseT m/board adaptor and switching your n/work to 100BaseT instead. You can use standard intel NICs with Xterm s/w f/w at the latest level.

Later,
Bill

[Bill McNAMARA_1]

just to add, if you boot all your xterms simultaneously, you will bottleneck your boot server via tftp. tftp loads all binaries completely at once.. switching to NFS which allows fseeks loads required portions of programs only.. and soft of pages in required bits when needed..
You might want to look at not loading unnecessary Xserver extensions such as the audio, Xtouch etc.. specified in /opt/hp^xt/enware2/xthome/bin/directives to quicken up the boot (and lower the network transfer, but ideally one server should boot only up to 50 xterms.
XDM server should be distributed to minimise Xtraffic.

I believe there is some X protocol compressor on hpux.cs.utah.edu but possibly won't work with the xterm...

Later,
Bill

[Robin Abecasis]

Thanks for your comments. Currently we have assigned just over 200 XTerms per TFTP server. We have multiple applications and multiple application servers. There is no NFS on our network due to its security limitations. All un-necessary extensions have been removed.

Its not that we want to minimize the X traffic, i am just interested in load balancing the initial hit that the TFTP servers get when over 4000 XTerms all boot up at once.

I assume that there are two types of load balancing, hardware and software solutions. I'd prefer a software solution if anyone knows of one...

Cheers,
Robin

[Bill McNAMARA_1]

Have you identified your bottle neck as network rather than disk io to xthome, there is not much you can do other than a network h/w overhaul.

SW solutions will have to be compatible with the xterm which is unlikely seeing as its discontinued h/w, so you really need to look at some caching switch mesh.

100BaseT if you're not using it would be the best solution, and/or scheduled reboots via cron to not all occur at once. Youre probably getting a lot of collisions and retrans, so should be using non blocking switches rather than hubs for your terms to help keep io reliable and sustainable.. what do hp suggest?

Traffic d/l simultaneously is around 8000MB allowing 4MB per term (Xserver and kernel)
You should get GB ethernet in host and a GB to 100/10 hub or switch to terminal.

You might want to get the Flash File System local to the xterm which will allow local storage of the Kernel, drivers xterm and fonts, allowing quicker boots, but of course more management.

If some terms are left blocked in boot your might want to enter in the tftp boot path 3 times via the remote config to make sure that if the path fails on first boot it'll at least try again before halting. This'll get some more of them up at once.

Later,
Bill

[Bill McNAMARA_1]

Where did you get so many xterms btw? You probably have a large percentage of the world market supply.. the only site using so many would be the NYSE/AMEX... and rebooting all simultaneously.. would that be you?

Later,
Bill

[Alex Glennie]

Hey Bill didn't one of the UK's customers build there own load balancing add-on S/W which was based on HP's implementation of enware ?

Did the xterminal Labs get involved or assist on this d'ya think ? Or are you not familiar with the site in question ? .... I could do some digging ?

[Bill McNAMARA_1]

yeah Alex, that was Philips, but it was XDMCP switching to direct login depending on server load, so more on the Xserver side than the boot side.

On the other hand Barclays, had similar issues I believe, but withing supported boot loads using tftp, that were worked around before fixed by specifying tftp boot host more than once.

imho, the problem isn't xterm here, it's lan load. I think any network scanner will verify that.

Later,
Bill

[Robin Abecasis]

Thanks again for your ideas/comments - you are indeed correct, this is for the NYSE.

Most Xterminals already have Flash's, and there are plans to upgrade to 100BaseT, but this is a big project as you can imagine. We are using switches already.

Do you know if HP's use of TFTP as regards the XTerminals and their downloads is standard? If it is then surely a s/w solution for load balancing should be able to handle it, most seem to work on an IP protocol (WWW, DNS, FTP & Mail seem to be the popular ones).

Yeah, this is purely to even out the network usage across the TFTP servers - and its a pain to manually assign each new XTerminal its primary/backup TFTP in such a way that we keep the number of client distributed. That's why i was hoping for a simple (sic!) s/w load balancing product. Sounds like there's a little whole in the market here...

Thanks again,
Robin

[Bill McNAMARA_1]

I thought you guys had this done with the gated daemon somehow or other?

You should really be opening up a call with WTEC/NARC. They should have a supported/qualified solution.

As far as tftp being standard goes, yes. The specs should be in the manual following some RFC guideline.

As far as the solution goes I'd try to leave the xterm out of it unless going to 100BT.

Good luck,
Bill