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1612 discussions

KVM usb to serial converter issue....
by Tom Bishop 11 Jan '11

11 Jan '11

So I have something that I am trying to do in kvm that requires a usb to serial converter...that goes to a serial device. I pass the usb to serial device via a physical device and win7 discovers the device and assigns it a com port...all is good until I reboot win7 and I have to remove the device and re-add it from kvm...it then discovers it and assigns it a new com port. If I look in windows it appears that the com port it was originally using shows that it is in use..so I think that is the issue but not sure how to correct it so every time I reboot I dont have to re-add... my xml snippet... <hostdev mode='subsystem' type='usb' managed='yes' <source> <vendor id='0x067b'/> <product id='0x2303'/> </source> </hostdev> Any thoughts...would be appreciated...Thanks! :)

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Discover DHCP addresses
by AustinPowered 21 Dec '10

21 Dec '10

Is there is way on the command line of the host to determine the IP address of a guest virtual machine? Perhaps a way to find out what addresses have been assigned by the DHCP server on the host? Thanks, -- AustinPowered

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User Space Memory Shared with VM's
by AustinPowered 21 Dec '10

21 Dec '10

I would like to pass data from user space memory on the host to user space on the guests. What is the best performing way to implement this? Thanks, -- AustinPowered

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Xen version
by Paul Piscuc 16 Dec '10

16 Dec '10

Hi, We are thinking of using CentOS with XEN in production, but we are facing some issues regarding the 3.0.3 version of the xen hypervisor and windows paravirtualization. The drivers we are using are from here ( http://wiki.xensource.com/xenwiki/XenWindowsGplPv) The solution we found is upgrading to xen 3.4.2, using a strange repository (gitco.de), and everything seems to work. Now the question is: would you recomand using the 3.0.3 kernel provided by CentOS in production and searching for other paravirtualization drivers, or go with 3.4.2? Is this version of the hypervisor stable?

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OpenNode (CentOS + OpenVZ + KVM) Management Server preview is now available
by Andres Toomsalu 15 Dec '10

15 Dec '10

Hi, We have been releasing first public preview of OpenNode Management Server and its ajax Web Management Console. OpenNode host (eg bare-metal OpenNode ISO installer) is basically a CentOS + OpenVZ + KVM + libvirt + func mashup with customized installer - while OpenNode Management Server provides central management features based on func and libvirt layer and including a RPC API server + ajax Web Management Console on top of func infrastructure - together with secure HTML5 VNC and SSH VM consoles. More info about OpenNode in general: http://opennode.activesys.org/ OpenNode Management Server release announcement: http://opennode.activesys.org/single/news/opennode-management-server-and-it… Regards, -- ---------------------------------------------- Andres Toomsalu, andres(a)active.ee CEO, Active Systems LLC

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Storage performance
by Dennis Jacobfeuerborn 14 Dec '10

14 Dec '10

Hi, I recently did some benchmarking on a Rackspace VM and was surprised that bonnie++ showed a read throughput of almost 500MB/sec. Does anyone have an idea how they achieve these speeds in a shared environment? While you can achieve this with a RAID easily these days once you have lots of VMs accessing that array I would expect that speed to go down quite a bit. Was I just lucky that I was the only one accessing the disks that way at that moment or how do they keep up with this kind of demand? Regards, Dennis

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VMs died due to hanging httpd processes
by Dennis Jacobfeuerborn 12 Dec '10

12 Dec '10

Hi, about an hour ago two web-serving VMs died at the same time with the following error on the console: INFO: task httpd:4304 blocked for more than 120 seconds. "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. httpd D 00af1f714d1112e2 0 4304 22471 4305 4303 (NOTLB) ffff88006574bdc8 0000000000000282 00000000000041f8 ffff88006574bea8 000000000000000a ffff88009747b820 ffffffff804f4b00 00000000001a5eee ffff88009747ba08 ffff880095be5015 Call Trace: [<ffffffff8022d03c>] mntput_no_expire+0x19/0x89 [<ffffffff8020eeae>] link_path_walk+0xa6/0xb2 [<ffffffff80263a7e>] __mutex_lock_slowpath+0x60/0x9b [<ffffffff80223f33>] __path_lookup_intent_open+0x56/0x97 [<ffffffff80263ac8>] .text.lock.mutex+0xf/0x14 [<ffffffff8021b52d>] open_namei+0xea/0x6d5 [<ffffffff8029cb30>] set_process_cpu_timer+0xc7/0xd2 [<ffffffff80227caa>] do_filp_open+0x1c/0x38 [<ffffffff8021a364>] do_sys_open+0x44/0xbe [<ffffffff802602f9>] tracesys+0xab/0xb6 Monitoring show that in a timeframe of about 3 minutes the load on the systems shot up to over 400 before they died. Since MaxClients is set to 512 I suspect that the processes had a mass-lockup with each process constantly causing a load of 1 (similar to what happens when a process hangs on an NFS mount point). One of the two VMs acts as a NFS server and exports directories to the other VM (but doesn't mount any external NFS sources itself). What is strange is that both system locked up at the same time since they are running on two different physical hosts. The hosts run Centos 5.3 while the VMs run Centos 5.5 as PV Xen guests. Since the call trace looks identical on both cases I wonder if anyone has an idea what exactly went wrong here? Regards, dennis

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Re: [CentOS-virt] IBM GPFS filesystem
by Evan Fraser 03 Dec '10

03 Dec '10

Hi Adam, GPFS nodes can be licensed in two different ways. As a node with storage locally attached (called NSDs), or as a client node that connects to NSD servers. My Virtual servers are client nodes, and thus have an appropriate client license (these are cheap). They connect via GPFS's RDMA over Infiniband to my GPFS NSD servers which are a much more expensive license. The purpose of me doing it this way was to let me use storage already allocated to GPFS for my cluster without having to dedicate any luns to Virtual servers. Cheers, Evan. >Hi Evan, > >Thanks for the response. Just out of curiosity, do you have to pay the >extra licensing costs for each CentOS node? > >best, > >...adam This message and any attachments contain information that may be RMS Inc. confidential and/or privileged. If you are not the intended recipient (or authorized to receive for the intended recipient), and have received this message in error, any use, disclosure or distribution is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to the e-mail and permanently deleting the message from your computer and/or storage system.

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IBM GPFS filesystem
by Adam Wead 03 Dec '10

03 Dec '10

Hi all, I was wondering if anyone might be able to speak about using IBM's GPFS filesystem as a means of storing virtual guests in a clustered environment with CentOS as the nodes and KVM as the hypervisor? I'm looking at using IBM's TSM software for archiving data from disk to tape. This requires buying a license for GPFS which is used in conjunction with TSM but can also be used as a clustered filesystem as well. As I understand it, GPFS can work with CentOS so long as you're using the right kernel. Is anyone out there using CentOS+GPFS for their virtualization environment? many thanks in advance, ...adam

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PXDI; Automated Xen 4.0.1 + 2.6.32 dom0 installer for RHEL 6
by Digimer 22 Nov '10

22 Nov '10

I tool Pasi Kärkkäinen's tutorial[1] that he announced on Thursday and turned it into an automated installation program called PXDI. - http://wiki.alteeve.com/index.php/Pxdi I've tested it on ~9 machines and, so far, it has worked. Of course, this is a small sample set and could use much more testing. *hint* :) As it is built now, it can take a "minimal" Red Hat Enterprise Linux 6.0 x86_64 install (+perl) and completely built and install qemu, (patched) libvirt, xen 4.0.1 and a 2.6.32 dom0. It also adds itself to /boot/grub/grub.conf, so it should be a matter of run, wait, reboot, done. *PLEASE* don't run it on a server you care about. I have done my best to avoid errors, but I can make promises that it won't mess up your machine. Run it on test servers only, please, until more testing is done. If the installer aborts at any time, it is smart enough to (mostly) know what has already been done and will pick up where it left off. So it should be safe to run several times if needed without problem. Of course, I hope one run will be enough. :) Eventually we hope to have RPMs in repos so most users won't need this. For now though, I hope this will do. I would *love* to hear feedback; Good, bad or otherwise! Digimer 1. http://wiki.xen.org/xenwiki/RHEL6Xen4Tutorial -- Digimer E-Mail: digimer(a)alteeve.com AN!Whitepapers: http://alteeve.com Node Assassin: http://nodeassassin.org

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