Hi Olivier, On 04/03/2012 10:31 AM, Olivier wrote:
For training sessions, I'm evaluating the possibility to use a single physical server to host 5 virtual servers, each with its own Dahdi PCIe card, instead of using 5 physical machines, hoping a single physical server would easier to transport, more quiet and cheaper to provision and maintain.
Nice idea. Hope you can pull it off.
As you can guess, each machine shouldn't be heavy loaded (a couple of calls, for each). If that matters, each machine would get Asterisk 10. One virtual server would play PSTN role and provide E1/T1 connectivity to each 4 server, playing as our favorite B2BUA. I hope servers with 5 PCI slots can be found here and there but I'm worried about IRQs, timing issues and the likes.
Afaik PCIe has less problems with interrupt sharing than PCI. But timing issues are always a risk when it comes to Virtualization. Maybe you can improve it by using a quadcore or octocore cpu and pin each VM to its own core(s). Reducing I/O also helps so create ramdrives and put stuff on tmpfs where possible. Obviously you need enough ram in the box to facilitate this.
1. Beside PCI assignment, which virtualization feature is required to build such machine ? In other words, is reading "PCI-assignment" in Xen, LXC or equivalent datasheet enough ?
Last time I tried this was with a Sangoma card trying to make it available in a CentOS VM which ran on top of Fedora 15. At the time I could not make it work. Maybe things have improved since then. And you can easily test it by just setting up a CentOS 6.2 or Fedora 16 host (or whatever your favorite distro is) with a card, create the VM and try to make the card show up in the VM and get it recognized by DAHDI.
Alternatively, if it does not work, you could try the ISDN BRI route with for example a Digium B410P, Sangoma B500/B700 or Eicon Diva Server BRI card running on the host and attach a number of USB ISDN devices (HFC-USB chipset) which are then passed to the VMs. That's assuming that USB passthrough works better than PCIe passthrough. This requires the mISDN code from misdn.eu but if you really need something to work and your initial idea won't fly then this might be an option.
2. How many PCIe cards can be "safely" inserted inside a server, without any virtualization ? Does this figure change when virtualizing
Afaik the limit is determined by how many PCIe slots you have. That is assuming the load is as light as you described. Blasting four 10G Ethernet cards full with data will probably not work very well in this scenario with a small PC.
Good luck! If you figure out a way to make this work please share your experience on the list.
Regards, Patrick -- _____________________________________________________________________ -- Bandwidth and Colocation Provided by http://www.api-digital.com -- New to Asterisk? Join us for a live introductory webinar every Thurs: http://www.asterisk.org/hello asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
