Discuss June 2012

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185 participants
178 discussions

CentOS 6 bridging problem.
by Rafał Radecki 17 Jul '12

17 Jul '12

Hi all. I have currently an OpenVZ server: uname -a Linux vader8.superhost.pl 2.6.32-042stab055.16 #1 SMP Fri Jun 8 19:22:28 MSD 2012 x86_64 x86_64 x86_64 GNU/Linux cat /etc/redhat-release CentOS release 6.2 (Final) lspci | grep -i eth 01:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 03) cd /etc/sysconfig/network-scripts cat ifcfg-eth0 DEVICE="eth0" BOOTPROTO=none NM_CONTROLLED="no" ONBOOT="yes" TYPE="Ethernet" HWADDR=00:25:22:0D:C2:2A DOMAIN=domain.eu IPV4_FAILURE_FATAL=yes IPV6INIT=no NAME="System eth0" UUID=5fb06bd0-0bb0-7ffb-45f1-d6edd65f3e03 BRIDGE=vmbr0 cat ifcfg-eth0.20 DEVICE=eth0.20 BOOTPROTO=none ONBOOT=yes VLAN=yes BRIDGE=vmbr20 cat ifcfg-vmbr20 DEVICE=vmbr20 BOOTPROTO=none DHCPCLASS= IPADDR=10.20.0.108 NETMASK=255.255.0.0 ONBOOT=yes TYPE=Bridge cat ifcfg-vmbr0 DEVICE=vmbr0 BOOTPROTO=none DHCPCLASS= IPADDR=195.218.152.219 NETMASK=255.255.255.0 ONBOOT=yes TYPE=Bridge cat ifcfg-vmbr0:1 DEVICE=vmbr0:1 BOOTPROTO=none IPADDR=192.168.2.203 NETMASK=255.255.255.0 ONBOOT=yes cat ifcfg-venet0 DEVICE=venet0 ONBOOT=yes STARTMODE=onboot route -n Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.2.0 0.0.0.0 255.255.255.0 U 0 0 0 vmbr0 195.218.152.0 0.0.0.0 255.255.255.0 U 0 0 0 vmbr0 10.20.0.0 0.0.0.0 255.255.0.0 U 0 0 0 vmbr20 169.254.0.0 0.0.0.0 255.255.0.0 U 1003 0 0 vmbr0 169.254.0.0 0.0.0.0 255.255.0.0 U 1006 0 0 vmbr20 0.0.0.0 193.218.152.1 0.0.0.0 UG 0 0 0 vmbr0 iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination So I have a setup in which: - eth0 is my physical interface - it is bridged with vmbr0 with ip 195.218.152.219 and this address is accessible across the network - eth0.20 is a logical interface in VLAN 20 on eth0 - it is bridged with vmbr20 with ip 10.20.0.108 and this address IS NOT accessible across the network - vmbr0 bridge has an alias vmbr0:1 with ip 192.168.2.203 and this address is accessible across the network When I set up the network for testing: - eth0 as a physical interface 195.218.152.219 - eth0.20 as a VLAN interface 10.20.0.108 both addresses are accessible across the network (VLANs on the switch are set up correctly, VLAN 1 untagged, VLAN 20 tagged). Do you see an error in my configuration? Why is 10.20.0.108 not available? Best regards, Rafal.

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3TB usb drive won't mount
by Bent Terp 17 Jul '12

17 Jul '12

Hi list! I have a 3TB usb drive with an NTFS filesystem on it, that I can't mount.: [bent@bnlaptop ~]$ sudo /sbin/mount.ntfs-3g /dev/sdb1 /mnt Failed to read vcn 0xf28: Input/output error Failed to mount '/dev/sdb1': Input/output error NTFS is either inconsistent, or there is a hardware fault, or it's a SoftRAID/FakeRAID hardware. In the first case run chkdsk /f on Windows then reboot into Windows twice. The usage of the /f parameter is very important! If the device is a SoftRAID/FakeRAID then first activate it and mount a different device under the /dev/mapper/ directory, (e.g. /dev/mapper/nvidia_eahaabcc1). Please see the 'dmraid' documentation for more details. On a Win7 machine there are no problems and chkdsk can't find anything wrong with the filesystem. I can mount 1TB drives using ntfs-3g without problems, so the driver doesn't seem to be the issue. I've tried both CentOS6.2 and Fedora16 with the same result. Any suggestions? with kind regards, Bent Terp

5 7

XEN or KVM - performance/stability/security?
by Rafał Radecki 14 Jul '12

14 Jul '12

Hi all. I am currently building a small test cloud based on Eucalyptus 2.0.3 and CentOS 5.8 x64. I have a choice which hypervisor to use: KVM or XEN. KVM is the default in CentOS 6 but I have read also many good things (for example PV guest machines, isolation between Dom0 and DomU) about XEN. Key factors from my opint of view are: - stability (which one runs more smoothly on CentOS?) - performance (XEN PV/HVM(with or without pv drivers) vs KVM HVM(with or without pv drivers)) - security Could you share your experience in these areas? Best regards, Rafal Radecki.

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Re: [CentOS] Best way to duplicate a live Centos 5 server?
by Cal Sawyer 11 Jul '12

11 Jul '12

Subject: Re: [CentOS] Best way to duplicate a live Centos 5 server? To: CentOS mailing list <centos(a)centos.org> On Mon, Jun 18, 2012 at 11:21 AM, Cal Sawyer <cal-s(a)blue-bolt.com> wrote: >> > >> > ReaR has suddenly become very interesting to me, probably explaining why >> > it utterly fails to work properly (for me).I'm using 1.13 to pull a >> > USB-based recovery image, but there's an error in the >> > backup/NETFS/default/50_make_backup.sh script that doesn't mount the USB >> > device after the mkrecovery step, so subsequent tar fails on write to >> > the non-existent mountpoint. I fixed that, but on recovery it fails to >> > mount the necessary directories on the restore drive as well, so "rear >> > recover" quickly bombs out. Is anyone having any success actually using >> > ReaR on CentOS 6.x? - csawyer > It intentionally doesn't deal with drives the kernel has marked as > removable. I had trouble with that with the main drives on a SAS > hotswap backplane in an earlier version but I think that is fixed now. > > I'd recommend asking how to override this on the ReaR mail list. > While the code seems usable (and yes, I have succeeded in using it on > Centos 6x.), the documentation either doesn't exist yet or is very out > of date. But, the authors are very responsive and it would be good > to let them know about any bugs or usability problems. The mail list > is still at sourceforge although the code has been moved to github and > there is talk of moving the list elsewhere. > > -- Les Mikesell lesmikesell(a)gmail.com ReaR hasn't posed any insurmountable problems with USB removable media but i can see SATA/SAS needing some massaging in the device detection dep't. Yes, i've gotten myself on the ReaR mailing list now. You're right - documentation is pretty dire. Guess i'm not alone in hating doing it. USB backup is broken due to the order in which path variables get set - sure is lot of fun trawling through the scripts to find out what gets set when. Hope the ReaR maintainers are interested in this and haven't gotten themselves mired in tape archive integration - i would have thought USB backup was the winner in terms of getting broad acceptance as a bare-metal DR solution. However, when it works - wow. Just restored an HP dl360 w/HWRAID to a Presario desktop machine and it lives! No network, but that's small beans compared to the larger win. - csawyer

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CentOS 5.8 crash/freeze running VMware
by Michael Eager 10 Jul '12

10 Jul '12

Hi -- I have a server running CentOS 5.8. It has a 6-core AMD processor, 16Gb memory, and a RAID 5 file system. It serves as both a file server and to run several VMware virtual machines. The guest machines run Windows 7 and various versions of Linux. The system is running the latest version of VMware Workstation. Until recently, I started VMs using the VMware Workstation GUI. The system has been very stable and seldom crashes. Recently, I set up an init script to start several VMs at boot time using the vmrun command. This appeared to work correctly, but the system has become unstable, freezing at various times. When the system freezes, there is no console response and it does not respond to a ping. There is nothing in syslog to indicate any error. The script started 8 VMs. I've cut back to now running 4 VMs and the system appears stable. Is there some relation between the number of cores and the number of VMs one can run? Is there something else which might cause the system to crash when running multiple VMs? Any suggestions to identify why the system crashed? -- Michael Eager eager(a)eagercon.com 1960 Park Blvd., Palo Alto, CA 94306 650-325-8077

4 5

NIS expiration of passwords
by Fabien Archambault 07 Jul '12

07 Jul '12

Dear all, I have a NIS server which shares a database of users between some computers (nodes exactly) and I would like that, on the first login, the user changes its password. So, on the NIS server I have made: chage -d 0 USER Then: # cd /var/yp # make On the NIS server I have: chage -l USER Last password change : password must be changed Password expires : password must be changed Password inactive : password must be changed Account expires : never Minimum number of days between password change : 0 Maximum number of days between password change : 99999 Number of days of warning before password expires : 7 I would believe this information is shared from the server to the other computers but here users still can connect (via SSH). If I try to get the information on the user connected I have: # chage -l USER user 'USER' does not exist in /etc/passwd This looks normal as there is no user there but then I do not know how to enable the expiration information through NIS. Do someone has an idea? Thanks, Fabien

3 2

Question about storage for virtualisation
by Nicolas Ross 03 Jul '12

03 Jul '12

Hi ! I'm about to deploy a new server that will host several virtual host for mainly website hosting purposes. My server will be a Xeon 3440 or 3450 with 32 gigs of ram (the max of that board). So I will have 8 logical cores. At the moment, I don't know how many vms I will have, in the order of 5 or 6. I am quite new to managing VMs, I did play alot with them over the course of the last couple of weeks. I used kvm to startup and manage my vms and my main source of info was this blog entry : http://blog.mattbrock.co.uk/2012/02/12/virtualisation-with-kvm-and-lvm-on-c… I have some general questions about VM. If I set vcpu let's say to 2-3 for a single vm, does this mean that those CPU are dedicated to that vm or many vm can share the same physicial cpus ? So, I was wondering what's the best for managing storage for VMs ? I see mostly recomandations for LV for storing VM's disks. It seem to helps to create snapshots for backup purposes. Is this the fastest way of creating backups ? And will data access be faster that if I use regular files ? In my case, the "main" setup of each vm is rather simple. The minimal OS, updates, my own httpd, my own php a couple of other packages. So restoring a VM from scratch can take less than an hour. So I was thinking of not taking snapshot of the whole VM and only sync the data partition. As for the guest paritions, I am accustomed of separating my servers disks with separate /, /usr, /var, /home and /data partitions. I can't recall today why I started doing this, 15 years ago, but I still like it that way and continue to do so. Do I still "need" to do this with VMs ? Thanks for the help !

12 25

A parted issue
by m.roth＠5-cent.us 30 Jun '12

30 Jun '12

We just got in a few server-class drives. They're Seagate Constellations, 3TB. I went to partition and format, and did a mklabel gpt in parted. Ooops. It claims Sector size (logical/physical): 512B/512B After data sheet that doesn't tell me, and a long wait*, I spoke to a Seagate tech, who agreed that it *is* 4k physical. This is CentOS 6.2 Anyone know any way to correct this, or if it's a problem if I manually align the partition to sector 64, or 1M? mark * Seagate "live chat" announced that it doesn't support my browser (firefox!!!), only IE, Safari, and chrome. I told the tech of my complaint and surprise to his manager.....

2 1

Universal server hardware platform - which to choose?
by Rafał Radecki 29 Jun '12

29 Jun '12

Hi all. I am working for a hosting provider in Poland. We are currently searching for an universal, extensible hardware platform which we would like to use in our server infrastructure. The platform should have: - possibility to install up to 32GB of RAM and at least 4 slots for it; - at least 6 SATA ports; - the possibility to use SAS disks; - at least one 1Gb/s network interface and the possibility to add another one; - size of 2 or 3U; - hot swap for disks. We are looking for a solution in which we would be able to deploy a basic server with for example 2 SATA disks, 8GB of RAM, 1 NIC, 4 cors and to be able to use the same enclosure and motherboard and extend it to deploy a more heavy-duty server with for example 6 SATA disks, 24GB of RAM, 2 NICs, 8 cors. Which manufacturer can you recommend and why? We are looking for something rather not expensive but reliable which has a good support. All servers will be based on CentOS5/6 :) Best regards, Rafal Radecki.

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How to handel smtp to public servers
by Götz Reinicke 29 Jun '12

29 Jun '12

Hi, we do have some subnetworks for private computers, which are allowed to use there public smtp servers like msn, web.de or whatever with the users private accounts. All our own computers have to send mail trough our mailserver with user authentication. From time to time we are faced with the fact, that a virus infected private notebook sends spam and we are told by our ISP to take care :) What might be a good choice to allow clients to send unrestricted transparent mails (= use smtp(s)) but we can monitor? E.g. like a redirect or proxy for smtp? I like to know which private computer sends lot of mail. :) Thanks for any hint and suggestion. /Götz -- Götz Reinicke IT-Koordinator Tel. +49 7141 969 82 420 Fax +49 7141 969 55 420 E-Mail goetz.reinicke(a)filmakademie.de Filmakademie Baden-Württemberg GmbH Akademiehof 10 71638 Ludwigsburg www.filmakademie.de Eintragung Amtsgericht Stuttgart HRB 205016 Vorsitzender des Aufsichtsrats: Jürgen Walter MdL Staatssekretär im Ministerium für Wissenschaft, Forschung und Kunst Baden-Württemberg Geschäftsführer: Prof. Thomas Schadt

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Discuss June 2012