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  • dom0 enable IPv6 for guests

    - by user98651
    I am looking at deploying IPv6 to my virtual machines. Right now I have v6 working great on the dom0 using a 6in4 provided by Hurricane Electric as I do not have native v6. However, I would like to distribute some of the /48 I am receiving to the domUs (/64 per machine would be ideal, but I am open to your suggestions). Static configuration on the domU side is fine. All I want to accomplish is getting the traffic to pass through the dom0 to the domU. To say the least, I'm still trying to wrap my head around all the virtual interfaces and bridges Xen creates. Yes, I have Googled around for this a bit and have not found anything great. I tried using two "vif-route6" bash scripts with no luck (possibly due to my ignorance with Xen networking). I am still stuck (mainly in how to configure the dom0). I would like to imagine this problem is relatively easy to solve and I look forward to your suggestions and help! Edited post to clarify my end goal: getting IPv6 to domU guests. I am completely open to suggestions but am hoping for something other than setting up a tunnel for every guest.

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  • Xen 4.1 host (dom0) with blktap disks ("tap:aio:") not connecting

    - by Manwe
    Problem using blktap with xen-4.1 running Ubuntu Precise stock kernel with dom0 xen-4.1. I get: [ 5.580106] XENBUS: Waiting for devices to initialise: 295s...290s. ... [ 300.580288] XENBUS: Timeout connecting to device: device/vbd/51713 (local state 3, remote state 1) And some syslog lines: May 17 13:07:30 localhost logger: /etc/xen/scripts/blktap: add XENBUS_PATH=backend/tap/10/51713 May 17 13:07:31 localhost logger: /etc/xen/scripts/blktap: Writing backend/tap/10/51713/hotplug-status connected to xenstore. with tap:aio: disk lines. file:/ works. disk = [ 'tap:aio:/data/root.img,xvda1,w', ] Problem exists with lucid and precises domU kernels and both guests work in Ubuntu hardy dom0 Host 64bit 2.6.24-28-xen xen-3.3 3.2.0-24-generic #37-Ubuntu SMP Wed Apr 25 08:43:22 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux Distributor ID: Ubuntu Description: Ubuntu 12.04 LTS Release: 12.04 Codename: precise

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  • compile kernel 2.6.34 for Ubuntu Lucid for xen dom0 / pvops

    - by andreash
    Hi there, I'd like to compile a recent Linux kernel (2.6.34) for my Ubuntu 10.04 Lucid Lynx AMD64 box, mainly because I'd like to use it as a dom0 kernel with the recent xen4. There's plenty documentation on the web about how to compile a kernel 'Debian style'. But what I think would be nice to start with an 'official' Ubuntu config to be sure not to miss any important things and having to recompile over and over again. So what I'd like to do is compile 2.6.34, but starting with the 'official' /boot/config-2.6.32-XX from Ubuntu Lucid. The question is: How do I best do that? If I just take the config from 2.6.32, the new features from 2.6.33/34 won't be in the config. So what I'd like to do is somehow the 2.6.34 config with the original 2.6.32 one from Ubuntu. How can I best do that? Does it even make sense? Is there easier ways to achieve what I want? Thanks for your insight! A. PS: I just found a linux-image-2.6.32-bpo.4-xen-amd64 package on backports.org, but no information about it. Would it work as a dom0 kernel on Lucid?

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  • Xen dom0 reports incorrect amount of RAM with dom0_mem set

    - by xen_amnesiac
    I've done a fair bit of searching about this, but have found nothing that answers my question. I have a system with 6GB of RAM which acts as a Xen server. For reference, it runs Ubuntu 12.04. I've set the kernel parameter dom0_mem:512M,max:512M in /etc/default/grub as follows: GRUB_CMDLINE_XEN_DEFAULT="dom0_mem=min:512M,max:512M" I've tried variations of that, with the same result. My question is this: With the above set, the dom0 reports in all applications a RAM amount of 422M. cat /proc/meminfo gives the following: $ cat /proc/meminfo MemTotal: 432472 kB MemFree: 54144 kB Buffers: 17640 kB Cached: 220104 kB SwapCached: 30172 kB Active: 136500 kB Inactive: 167780 kB Active(anon): 6156 kB Inactive(anon): 60516 kB Active(file): 130344 kB Inactive(file): 107264 kB Unevictable: 52 kB Mlocked: 52 kB SwapTotal: 1794044 kB SwapFree: 1682012 kB Dirty: 0 kB Writeback: 0 kB AnonPages: 39572 kB Mapped: 8048 kB Shmem: 136 kB Slab: 44324 kB SReclaimable: 22012 kB SUnreclaim: 22312 kB KernelStack: 1280 kB PageTables: 3840 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 2010280 kB Committed_AS: 329192 kB VmallocTotal: 34359738367 kB VmallocUsed: 313988 kB VmallocChunk: 34359417340 kB HardwareCorrupted: 0 kB AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 524696 kB DirectMap2M: 0 kB top, htop, free -m, and byobu's RAM monitor all report the same amount. At first I thought this was because of the onboard graphics borrowing some memory, but have now switched to a dedicated GPU and it persists. Is this normal behavior, or has something gone amiss? It's just about 100MB of RAM that's "gone", and I have no idea where it went. I understand that it's normal that not all RAM is available for allocation, but does the system really take an amount relatively high to the amount of RAM available?

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  • 32bit domU on 64bit dom0

    - by ModuleC
    I'm using 64bit Centos Dom0 with: 2.6.18-164.15.1.el5xen #1 SMP Wed Mar 17 12:04:23 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux recently i migrated some 32bit Centos domUs on this node. As by specs 32bit domUs should work with 64bit dom0. DomUs are paravirtualized, and everything works, except iptables limit. Anyways runing csf on domU will return following messages in dmesg: ip_tables: (C) 2000-2006 Netfilter Core Team Netfilter messages via NETLINK v0.30. ip_conntrack version 2.4 (2080 buckets, 16640 max) - 304 bytes per conntrack ip_tables: limit match: invalid size 40 != 28 ip_tables: limit match: invalid size 40 != 28 ip_tables: limit match: invalid size 40 != 28 ip_tables: limit match: invalid size 40 != 28 ip_tables: limit match: invalid size 40 != 28 ip_tables: limit match: invalid size 40 != 28 ip_tables: limit match: invalid size 40 != 28 Doing lsmod on both dom0 and domU is listing all iptables modules required as loaded. I've found this http://www.mail-archive.com/[email protected]/msg189433.html But didn't find anything for centos on this issue. Am I missing something?

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  • How to find dom0 name from hosted domU

    - by svigan
    I'm actually testing RHEL 5.3 with Xen between two servers in order to have a disaster recovery solution. So I'm playing with moving my domU from one dom0 server to the other server. Unfortunatly when somebody else move the domU I don't have any clue where my domain is hosted. I'm wondering where I can't find my dom0 name with inside domU. I'm looking for something like the gzonename command on a solaris sparse zone. I check inside /proc/xen but I don't see anything special except the dom0 kernel release. Does anybody know a wait to find this ?

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  • Capturing XEN Dom0 logs on Debian lenny ?

    - by Xavier
    I have a Dell server with Xen 3.2 (from Debian Lenny) running a Debian Lenny dom0. Since I am facing unexpected reboot without any clue in the debian logs, I would like to capture the Xen dom0 logs. Did anybody achieve this and how ? I tried to use the Dell serial port redirection without success.

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  • Ubuntu 10.04 (LTS) DomU on Debian Wheezy Dom0 Xen 4

    - by mdjp
    I have been forced to move from a Centos Dom0 xen 3 Centos + Ubuntu Lucid DomUs To Debian Wheezy Dom0 Xen 4 Ubuntu Lucid DomUs However although I can create new DomUs on wheezy I cannot get them to boot. pygrub returns Error: Bootloader didn't return any data I have ensured that the disks are the correct way around in the xen.cfg and also that the grub config is correct. If I try to run pygrub manually eg /usr/bin/pygrub /dev/volgroup/disk I get Illegal instruction can anyone offer me any advice on this? Thanks Matt

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  • Why is domU faster than dom0 on IO?

    - by Paco
    I have installed debian 7 on a physical machine. This is the configuration of the machine: 3 hard drives using RAID 5 Strip element size: 1M Read policy: Adaptive read ahead Write policy: Write Through /boot 200 MB ext2 / 15 GB ext3 SWAP 10GB LVM rest (~500GB) emphasized text I installed postgresql, created a big database (over 1GB). I have an SQL request that takes a lot of time to run (a SELECT statement, so it only reads data from the database). This request takes approximately 5.5 seconds to run. Then, I installed XEN, created a domU, with another debian distro. On this OS, I also installed postgresql, with the same database. The same SQL request takes only 2.5 seconds to run. I checked the kernel on both dom0 and domU. uname-a returns "Linux debian 3.2.0-4-amd64 #1 SMP Debian 3.2.41-2+deb7u2 x86_64 GNU/Linux" on both systems. I checked the kernel parameters, which are approximately the same. For those that are relevant, I changed their values to make them match on both systems using sysctl. I saw no changes (the requests still take the same amount of time). After this, I checked the file systems. I used ext3 on domU. Still no changes. I installed hdparm, and ran hdparm -Tt on both systems, on all my partitions on both systems, and I get similar results. Now, I am stuck, I don't know what is different, and what could be the cause of such a big difference. Additional Info: Debian runs on a Dell server PowerEdge 2950 postgresql: 9.1.9 (both dom0 and domU) xen-linux-system: 3.2.0 xen-hypervisor: 4.1 Thanks EDIT: As Krzysztof Ksiezyk suggested, it might be due to some file caching system. I ran the dd command to test both the read and write speed. Here is domU: root@test1:~# dd if=/dev/zero of=/root/dd count=5MB bs=1MB ^C2020+0 records in 2020+0 records out 2020000000 bytes (2.0 GB) copied, 18.8289 s, 107 MB/s root@test1:~# dd if=/root/dd of=/dev/null count=5MB bs=1MB 2020+0 records in 2020+0 records out 2020000000 bytes (2.0 GB) copied, 15.0549 s, 134 MB/s And here is dom0: root@debian:~# dd if=/dev/zero of=/root/dd count=5MB bs=1MB ^C1693+0 records in 1693+0 records out 1693000000 bytes (1.7 GB) copied, 8.87281 s, 191 MB/s root@debian:~# dd if=/root/dd of=/dev/null count=5MB bs=1MB 1693+0 records in 1693+0 records out 1693000000 bytes (1.7 GB) copied, 0.501509 s, 3.4 GB/s What can be the cause of this caching system? And how can we "fix" it? Can we apply it to dom0? EDIT 2: I switched my virtual disk type. To do so I followed this article. I did a dd if=/dev/vg0/test1-disk of=/mnt/test1-disk.img bs=16M Then in /etc/xen/test1.cfg, I changed the disk parameter to use file: instead of phy: it should have removed the file caching, but I still get the same numbers (domU being much faster for Postgres)

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  • Xen Bridge only working when IP Assigned

    - by m.sr
    Hey! Just had an (in my sense) obscure situation. I have a Xen Server with bridged networking. Everything works fine since month. A while ago i configuresd a second bridge. only some DomUs get an channel on this bridge - my Dom0 doesn't need to / should'nt use this bridge. So just 5 minutes ago while rebooting the xen host (because of an other problem with the UPS) i decided to removed the fixed ip from the the interface of the Dom0 which belongs to the second bridge. So after reboot i noticed that none of the interfaces on the second bridge is available. I couldn't find a problem. Everything was just like before the reboot, except the interface of the Dom0 had no IP address. After a while i tried to give the DomO interface of this bridge an IP again and ... BOOM ... everything is up and running again! WTF? Why is it important to have the interface of a bridge configured in the Dom0? Even when confiugured 'wrong' (complitely different netowkr settings as the network really hanging on the bridge) everythjing works fine ... I don't get it. Could please someone explain? Tnaks a lot!

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  • USB forwarding from dom0 to domU

    - by Karolis T.
    What are my options to forward two USB connected phones to xen guest? I've read about PCI-passthrough http://www.wlug.org.nz/XenPciPassthrough, but I'm sure usb controller in the server isn't a pci card. There's device level forwarding, but I need to forward two devices, this here doesn't say how to do it: http://www.olivetalks.com/2008/02/03/usb-forwarding-on-xen-it-just-does-not-work/ Would something as simple as: usbdevice = [ 'host:xxx', 'host:yyy', ] work? EDIT: I'm now starting a bounty. This is really important for me and for other people also, hoping someone who have this resolved will be able to help.

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  • Using more recent kernel for Xen Dom0 in production.

    - by thelsdj
    Does anyone have experience running Xen dom0 on a more recent kernel than the stock 2.6.18? What host distro are you running? What release of Xen (or hg/git changeset)? What set of patches are you using on kernel source? (Has anyone got the pvops dom0 stuff working in production or is it better to stick with something like the SUSE patches? Any other tips and tricks to running a more recent kernel version as dom0 would be helpful.

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  • What is a good OS to mess around with Xen Dom0?

    - by earlz
    Hello, I'd like to experiment some with Xen. My problem is I do not know which OS to try to install it with. I use OpenBSD, but it can not run as Dom0 or DomU at this point. I use Arch Linux on my website's VPS, so I know it and like it. The support for Xen just doesn't seem to be there though. Can anyone suggest a nice (preferably lightweight, so not SUSE and such) Linux distro or *BSD to mess around with Xen in a non-production environment?

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  • What steps should I take to debug this non-starting hvm virtual machine?

    - by Ophidian
    I have a dom0 machine running CentOS 5.4 with all the latest updates using Xen as my hypervisor. I am using Xen in part because this machine was set up prior to KVM being included in RHEL, and in part because KVM's network bridging configuration is not nearly as simple as Xen's. The dom0 machine is headless and I do all of my VM management via virsh from the command line. I have two hvm domU's: A web server running CentOS 5.4 A mail server running Gentoo Both VM's are backed by LV's on the dom0 but do not use LVM in the domU. Both have virtually identical libvirt configurations (differing by expected things like name, UUID, NIC MAC, VNC port, etc). The web server domU (WSdomU hereafter) does not start since applying the most recent kernel update (kernel-xen-2.6.18-164.15.1.el5.x86_64 and kernel-2.6.18-164.15.1.el5.x86_64 for the dom0 and WSdomU respectively). By 'not start' I mean it appears to be running but it does not use an CPU cycles, does not bring up a graphical console, and does not respond on the network. The WSdomU is listed as no state rather than the normal running or blocked in xentop. The mail server domU starts fine and functions normally. Here are the steps I have taken so far that did not solve the problem: Reboot the dom0 to see if things come up on their own Check xen dmesg on dom0 Check xend logs (a cursory viewing did not show anything blatant; specific suggestions of things to look for would be appreciated) Attempted to connect to the WSdomU's graphical (VNC) console from the dom0 Shutdown the mail server domU and attempt to start the WSdomU Check the SELinux labels on backing LV's (they're the same) Set SELinux to permissive and attempt to start the WSdomU Use virsh edit to try tweaking the WSdomU config virsh undefine, reboot, virsh define the WSdomU config dd the WSdomU LV to an .img file, copy it to my Fedora desktop and run it under KVM (works fine) What steps should I take next to debug this? I will edit in any additional configuration's requested in the comments.

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  • XCP Project Kronos syslog error: "irq ... : nobody cared" on Dom0 host

    - by Vlad Fedin
    One of our production clusters driven by XCP suddenly went uresponsive. After restart and some investigation we found such logs in dom0 machine syslog: Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659040] irq 339: nobody cared (try booting with the "irqpoll" option) Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659058] Pid: 0, comm: swapper/3 Tainted: G C O 3.2.0-24-generic #37-Ubuntu Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659060] Call Trace: Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659062] <IRQ> [<ffffffff810db37d>] __report_bad_irq+0x3d/0xe0 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659071] [<ffffffff810db605>] note_interrupt+0x135/0x190 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659074] [<ffffffff810d8e69>] handle_irq_event_percpu+0xa9/0x220 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659078] [<ffffffff8130ff3b>] ? radix_tree_lookup+0xb/0x10 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659081] [<ffffffff810d9031>] handle_irq_event+0x51/0x80 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659084] [<ffffffff810dc187>] handle_edge_irq+0x87/0x140 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659089] [<ffffffff813a8829>] __xen_evtchn_do_upcall+0x199/0x250 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659092] [<ffffffff813aa96f>] xen_evtchn_do_upcall+0x2f/0x50 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659096] [<ffffffff81666d3e>] xen_do_hypervisor_callback+0x1e/0x30 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659097] <EOI> [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659104] [<ffffffff810013aa>] ? hypercall_page+0x3aa/0x1000 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659107] [<ffffffff8100a1d0>] ? xen_safe_halt+0x10/0x20 Oct 26 20:32:03 hetzner-2-mrx kernel: [1797931.659110] [<fff IRQ 339 in cat /proc/interrupts: 339: ... xen-pirq-msi-x eth0 where eth0 is hardware NIC. While host machine seems to hang, guest machines continue to work, so our tiny internal monitoring on one of the virtual hosts logged something like that: [2012-10-26 20:31:51] [OK......] 200 OK : 113159149 ns [2012-10-26 20:32:40] [DISASTER] 500 Can't connect to [hostname]:80 (No route to host) : 47763284432 ns ... [2012-10-26 20:34:40] [DISASTER] 500 Can't connect to [hostname]:80 (No route to host) : 46894835070 ns [2012-10-26 20:34:57] [DISASTER] 500 Can't connect to [hostname]:80 (Bad hostname) : 16821741955 ns ... [2012-10-26 20:38:18] [DISASTER] 500 Can't connect to [hostname]:80 (Bad hostname) : 20103298289 ns [2012-10-26 20:38:37] [DISASTER] 500 Can't connect to [hostname]:80 (Bad hostname) : 17895754943 ns Host and guest OS: Ubuntu 12.04 LTS, 05:00.0 Ethernet controller: Intel Corporation 82574L Gigabit Network Connection Subsystem: ASUSTeK Computer Inc. Device 8369 Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+ Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx+ Latency: 0, Cache Line Size: 64 bytes Interrupt: pin A routed to IRQ 17 Region 0: Memory at fe500000 (32-bit, non-prefetchable) [size=128K] Region 2: I/O ports at e000 [size=32] Region 3: Memory at fe520000 (32-bit, non-prefetchable) [size=16K] Capabilities: <access denied> Kernel driver in use: e1000e Kernel modules: e1000e Any hints how to debug this?

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  • Debian network bridge configuration - /etc/network/interfaces

    - by Mathias
    I'm running a Lenny Xen dom0 hosting multiple virtual machines in a routed IP setup. To get an additional private subnet, I created the bridge xenbr0 in the dom0 with the following commands: brctl addbr xenbr0 ifconfig xenbr0 10.0.0.1 netmask 255.255.255.0 ifconfig xenbr0 up This works as expected, and domU interfaces are added to the bridge by Xen on VM start. My only problem is: how the heck do i specify this configuration in /etc/network/interfaces that it remains permanent and the bridge is available after a reboot? I tried the following config as found on a lot of tutorials: auto xenbr0 iface xenbr0 inet static address 10.0.0.1 netmask 255.255.255.0 network 10.0.0.0 broadcast 10.0.0.255 bridge_stp no I get 2 different errors, depending on if the bridge already exists or not. If it doesn't exist: root@dom0:~# brctl show bridge name bridge id STP enabled interfaces root@dom0:~# /etc/init.d/networking restart Reconfiguring network interfaces...if-up.d/mountnfs[eth0]: waiting for interface xenbr0 before doing NFS mounts (warning). SIOCSIFADDR: No such device xenbr0: ERROR while getting interface flags: No such device SIOCSIFNETMASK: No such device SIOCSIFBRDADDR: No such device xenbr0: ERROR while getting interface flags: No such device xenbr0: ERROR while getting interface flags: No such device Failed to bring up xenbr0. done. And if it exists: root@dom0:~# brctl show bridge name bridge id STP enabled interfaces xenbr0 8000.000000000000 no root@dom0:~# /etc/init.d/networking restart Reconfiguring network interfaces...if-up.d/mountnfs[eth0]: waiting for interface xenbr0 before doing NFS mounts (warning). RTNETLINK answers: File exists Failed to bring up xenbr0. done. Could anyone point me in the right direction please? The bridge works fine when created manually, i just need the right config file entries. The most tutorials I found add some devices to the bridge in the config, is that maybe the problem why it is not working? I don't have any interfaces I want to add to the bridge on creation as they get added later on VM start... Thanks, Mathias

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  • Xen PV packet loss

    - by Delphinator
    I'm having some serious issues with packetloss with one of my servers. This server is a somewhat old (P4-era) machine running Debian Squeeze and Xen 4.0. There are two domUs running on it (both also Debian Squeeze), one gateway and a fileserver. Unfortunatly the processor has no virtualization extensions, therefore only PV can be used. While investigating why our network seems to be slower than it should I found some pretty bad packet loss (~25%). After further investigation and several experiments I did a measurment between the dom0 and one of the domUs: Server listening on UDP port 5001 Receiving 1470 byte datagrams UDP buffer size: 110 KByte (default) ------------------------------------------------------------ ------------------------------------------------------------ Client connecting to dom0, UDP port 5001 Sending 1470 byte datagrams UDP buffer size: 110 KByte (default) ------------------------------------------------------------ [ 3] local 192.168.1.2(domU) port 33817 connected with 192.168.1.100(dom0) port 5001 [ 4] local 192.168.1.2(domU) port 5001 connected with 192.168.1.100(dom0) port 48606 [ ID] Interval Transfer Bandwidth [ 3] 0.0-10.0 sec 46.3 MBytes 38.7 Mbits/sec [ 3] Sent 33020 datagrams [ 3] Server Report: [ 3] 0.0-10.0 sec 46.2 MBytes 38.6 Mbits/sec 0.030 ms 89/33019 (0.27%) [ 3] 0.0-10.0 sec 1 datagrams received out-of-order [ 4] 0.0-10.2 sec 43.0 MBytes 35.3 Mbits/sec 13.074 ms 11575/42256 (27%) tl;dr: 27% packet loss from dom0 to domU with 50Mbit UDP packets. Same thing happens from anywhere in the network. The problem gets better for smaller bandwidths (0.047% for 5Mbit) and worse for higher (59% for 200Mbit) ones. I did increase the CPU-weight of the dom0, there is no swapping going on, and actual networking-hardware is not involved. I never expected Xen (or anything related) to drop packets, and I'm completly clueless what to try next.

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  • Transient network dropout for Xen DomU's

    - by Stephen C
    We've got a CentOS server running a cluster of virtuals. Occasionally the cluster's internal network drops out for a minute or so ... and then comes back. The problem is somehow related to the actual network traffic, but it is not a simple load issue. (The system is generally lightly loaded, and the problem occurs irrespective of actual load.) The setup: CentOS 5.6 on Dom0, various CentOS on the DomU's Hardware - a Dell R710 with a BroadCom NextXpress 2 NIC (sigh) using the latest drivers for the NIC from BroadCom Xen configured to use network-bridge and vif-bridge Some iptable tweaks to route an unrelated port to one of the virtuals. The system has one externally visible IP address, and Dom0 runs an Apache httpd configured with a number of virtual hosts each of which reverse proxies to web servers running on the virtuals. (The virtuals have to be NAT'ed, primarily because we don't have enough allocated public IP addresses.) The symptoms: Works fine most of the time. When someone tries to UPLOAD a large file to one virtuals, the internal network drops out ... for all virtuals: The Dom0 httpd sees a network timeout talking to the backend server on the virtual and reports a 502. A previously established ssh connection from Dom0 to any of the DomU's freezes. Our monitoring shows ping failures for traffic between virtuals. The Xen consoles to the DomU's do not freeze. No log messages in any log files that I can see, on either Dom0 or the DomU's ... apart from the Dom0 httpd logs. After a minute or so, the problem clears by itself. This is 100% reproducible. What we've tried: Downloading, building and installing the latest BNX2 driver on Dom0 Turning off MSI on the NIC - adding "options bnx2 disable_msi=1" to /etc/modprobe.conf Turning off tcp segmentation offload - "ethtool -K eth0 tso off". Sacrificing a black rooster at midnight. I've exhausted all my options apart from switching to KVM ... or slaughtering more roosters. Any suggestions?

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