Discuss January 2010

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323 discussions

Full Virtualized DomU won't boot
by Sergio Belkin 30 Jan '10

30 Jan '10

Hi, I use Centos 5.4 x86_64 kernel used is 2.6.18-164.11.1.el5xen I have a physical machine running Debian Etch (32 bit) and Debian Lenny and I virtualized the first one as follows: *Created a HVM DomU with Virt-Manager with a virtual disk file of 40000 M *Boot from LiveCD, and created a swap and a ext3 partitions (Yes, very simple layout). *Rsync'd files from root partition of physical machine to partition mounted on LiveCD on DomU. *Chrooted and edited files /boot/grub/menu.lst, /etc/fstab, etc/mtab, /boot/grub/device.map. *Then I rebooted from hard disk and stay freezed with the message "booting from hard disk" . But it doesn't boot at all from hard disk. I can boot using grub-rescue-cdrom, but if I try to install grub with grub-install it outputs: "The file /boot/grub/stage1 not read correctly" (I've tried --recheck option, and depmod and update-grub commands with no success) Output of file command on virtual disk file is: /virtuales/videodisk.img: x86 boot sector; partition 1: ID=0x82, starthead 1, startsector 63, 4273227 sectors; partition 2: ID=0x83, active, starthead 0, startsector 4273290, 77626080 sectors The DomU file is: DomU (file): name = "video" uuid = "54d25d78-b9d0-0159-542c-bb601cc936bb" maxmem = 1024 memory = 512 vcpus = 1 builder = "hvm" kernel = "/usr/lib/xen/boot/hvmloader" boot = "d" pae = 1 acpi = 1 apic = 1 localtime = 0 on_poweroff = "destroy" on_reboot = "restart" on_crash = "restart" device_model = "/usr/lib64/xen/bin/qemu-dm" sdl = 0 vnc = 1 vncunused = 1 keymap = "es" disk = [ "file:/virtuales/videodisk.img,hda,w", "file:/virtuales/isos/grub-rescue-cdrom.iso,hdc:cdrom,r" ] vif = [ "mac=00:16:36:0b:24:2d,bridge=xenbr0,script=vif-bridge" ] parallel = "none" serial = "pty" EOF With grub-rescue cd DomU can boot but as I've said can't install grub and loads also loopback interface. Please could you tell me what I am doing wrong? Thanks in advance!! -- -- Open Kairos http://www.sergiobelkin.com Watch More TV http://sebelk.blogspot.com Sergio Belkin -

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CentOS 5 i386 Live CD
by Mike McCarty 29 Jan '10

29 Jan '10

Johnny Hughes wrote: > I forgot to add that the password for root and centos is: > > 12qwaszx > > Johnny Hughes wrote: >> The CentOS Development team is pleased to announce the availability of >> the CentOS 5 i386 Live CD. [...] >> This CD has a non writable /usr directory, which means it is not able to >> have software installed on it after boot up. The CentOS team is working >> hard to create a Live CD for CentOS 5 that is based on the Fedora Live >> CD Project (that is writable in all directories and even able to be used >> for installs) ... unfortunately we were not able to get this working >> with CentOS 5 for this release. We hope to get that Live CD working by >> the release of CentOS 5.1. Did I miss some notices? I don't recall seeing another LiveCD. How is progress coming? Mike -- p="p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);} Oppose globalization and One World Governments like the UN. This message made from 100% recycled bits. You have found the bank of Larn. I speak only for myself, and I am unanimous in that!

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NFS vs SMb vs iSCSI for remote backup mounts
by Rudi Ahlers 29 Jan '10

29 Jan '10

Hi, I would like to get some input from people who have used these options for mounting a remote server to a local server. Basically, I need to replicate / backup data from one server to another, but over the internet (i.e. insecure channels) Currently we have been mounting an SMB share over SSH, but it's got it's own set of problems. And I don't know if this is optimal, or if I could setup something better. We don't have much control over the remote server, so I couldn't setup a VPN, or iSCSI or anything else. My options was FTP & SMB. But I want to move the backups in-house, to save bandwidth and have more control over what we do. So, with a new CentOS server & 2x1TB HDD's in RAID1 configuration, I can do pretty much whatever I want. The backup server(s) will serve backups for multiple servers, in different data centers (possible in different counties as well, I still need to think about this), so my biggest concern is security. We mainly use cPanel & DotNetPanel (Windows ServerS) , but also WebMin & VirtualMin, so I need to stick with their native backup procedures and don't really want to use a too technical backup system. The end users need access to the data 24/7, so having the remote share permanently mounted seems to be the best for this, then our support staff don't need to SSH into the servers and download the backups. With the mount, I can also use rsync backups, so an end user could restore only a single file if need be. NOW, the question is: Which protocol would be best for this? I can only think of SMB, NFS & iSCSI The SMB mounts have worked well so far, but it's not as safe, and once the SMB share is mounted, I can't unmount it until the server reboots. This isn't necessarily a bad thing, but sometime the backup script will mount the share again (I think this is a bug in cPanel) and we end up with 4 or 5 open connection to the remote server. NFS - last time I looked at it was on V3, which was IMO rather slow & insecure. iSCSI - this doesn't allow for more than one connect to the same share. Sometimes I user might want to download a backup directly from the backup server via FTP / SSH / a web interface, which I don't think will work. We also sometimes need to restore a backup on a different server (if for example the HDD on the initial server is too full), so this isn't possible. The remote shares also need to be mounted inside XEN domU's, or directly on CentOS / Windows servers. what would be my best option for this? -- Kind Regards Rudi Ahlers SoftDux Website: http://www.SoftDux.com Technical Blog: http://Blog.SoftDux.com Office: 087 805 9573 Cell: 082 554 7532

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Re: [CentOS] Lockup using stock r8169 on 4.8 in gigabit mode during heavy transfer on lan
by Tim Nelson 29 Jan '10

29 Jan '10

----- "Jason Pyeron" <jpyeron(a)pdinc.us> wrote: > I have no output in the logs, but /etc/init.d/network restart fixes > the issue. > I am rsync/scp (10GB) data from one 100MB Full duplex host to an ASUS > M3A78-EM > (RTL8111B/C). It locks up around the 1.5GB Tx mark. > If I ethtool -s eth0 autoneg off speed 100 duplex full it does not > happen again. > > Ideas? Part of the problem is that you mention r8169 kernel module in your subject but your hardware is RTL8111B. Realtek drivers are notorious for loading on improper hardware and appearing to work properly. You need to get the proper driver for your NIC. I've run into this countless times with the r8169 driver and non-r8169 Realtek NICs. And, on a side note, Realtek may possibly be the worst NIC out there, especially for server use. It may link at gigabit speed, but I bet a trusty old 3Com or Intel Pro 100 will get better throughput. Install a different NIC as fast as you can and never look back. --Tim

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Lockup using stock r8169 on 4.8 in gigabit mode during heavy transfer on lan
by Jason Pyeron 29 Jan '10

29 Jan '10

I have no output in the logs, but /etc/init.d/network restart fixes the issue. I am rsync/scp (10GB) data from one 100MB Full duplex host to an ASUS M3A78-EM (RTL8111B/C). It locks up around the 1.5GB Tx mark. If I ethtool -s eth0 autoneg off speed 100 duplex full it does not happen again. Ideas? -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- - - - Jason Pyeron PD Inc. http://www.pdinc.us - - Principal Consultant 10 West 24th Street #100 - - +1 (443) 269-1555 x333 Baltimore, Maryland 21218 - - - -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- This message is copyright PD Inc, subject to license 20080407P00.

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Re: [CentOS] NFS vs SMb vs iSCSI for remote backup mounts
by J.Witvliet＠MINDEF.NL 29 Jan '10

29 Jan '10

At any rate... if I were in your shoes and really restricted to the options you propose, I would go with CIFS mounts through IPSEC tunnels. Wouldn't IPSEC add more overhead than an SSH tunnel? -geoff I would *certainly* not use ssh-tunnels, on a line that is not 100% error free or with high latency. In general tcp-in-tcp tunneling is BAD. One likely gets the infamous snowbal-effect. As ipsec is lower in the protocol-stack (then openvpn) it has probably the lowest overhead. ssh-tunnels are the worst (just nice for a quick tunnel in SOHO-environments) ______________________________________________________________________ Dit bericht kan informatie bevatten die niet voor u is bestemd. Indien u niet de geadresseerde bent of dit bericht abusievelijk aan u is toegezonden, wordt u verzocht dat aan de afzender te melden en het bericht te verwijderen. De Staat aanvaardt geen aansprakelijkheid voor schade, van welke aard ook, die verband houdt met risico's verbonden aan het elektronisch verzenden van berichten. This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. The State accepts no liability for damage of any kind resulting from the risks inherent in the electronic transmission of messages.

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Re: [CentOS] NFS vs SMb vs iSCSI for remote backup mounts
by J.Witvliet＠MINDEF.NL 29 Jan '10

29 Jan '10

________________________________ From: centos-bounces(a)centos.org [mailto:centos-bounces@centos.org] On Behalf Of Rudi Ahlers Sent: Friday, January 29, 2010 12:23 AM To: CentOS mailing list Subject: Re: [CentOS] NFS vs SMb vs iSCSI for remote backup mounts On Fri, Jan 29, 2010 at 1:18 AM, nate <centos(a)linuxpowered.net<mailto:centos@linuxpowered.net>> wrote: Rudi Ahlers wrote: > nate, why not? Is it simply unavoidable at all costs to mount on system on > another, over a WAN? That's all I really want todo If what you have now works, stick with it.. in general network file systems are very latency sensitive. CIFS might work best *if* your using a WAN optimization appliance, I'm not sure how much support NFS gets from those vendors. iSCSI certainly is the worst, block devices are very intolerant of latency. AFS may be another option though quite a bit more complicated, as far as I know it's a layer on top of an existing file system that is used for things like replication http://www.openafs.org/ I have no experience with it myself. nate _______________________________________________ CentOS mailing list CentOS(a)centos.org<mailto:CentOS@centos.org> http://lists.centos.org/mailman/listinfo/centos Thanx nate, this is what I wanted to hear :) So, is there any benefit in using NFS over SMB in this case? Can't speak for NFS(3/4), but i can tell you that that smb-protocol combined with high latency is a recepy for disaster. We tried it from europe to the carribean (both sat or fibre) but users spent their time more complaining then working. Needed horrible expensive lan-optimesers at both end So perhaps nfs4 or afs (later is intended for geographically separated machines, afaicr) but certainly not smb! ______________________________________________________________________ Dit bericht kan informatie bevatten die niet voor u is bestemd. Indien u niet de geadresseerde bent of dit bericht abusievelijk aan u is toegezonden, wordt u verzocht dat aan de afzender te melden en het bericht te verwijderen. De Staat aanvaardt geen aansprakelijkheid voor schade, van welke aard ook, die verband houdt met risico's verbonden aan het elektronisch verzenden van berichten. This message may contain information that is not intended for you. If you are not the addressee or if this message was sent to you by mistake, you are requested to inform the sender and delete the message. The State accepts no liability for damage of any kind resulting from the risks inherent in the electronic transmission of messages.

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How to map ata#.# numbers to /dev/sd numbers?
by Stephen Harris 29 Jan '10

29 Jan '10

On my C5 machine (a Dell XPS420) I have a 500Gb disk on the internal SATA controller. I also have a SiI3132 dual-port multi-device eSATA card. This is connected to an external SATA array of disks. Now occasionally I see something like this in my logs ata7.01: exception Emask 0x0 SAct 0x0 SErr 0x0 a ction 0x0 ata7.01: irq_stat 0x00060002, device error via D 2H FIS ata7.01: cmd 25/00:08:47:1c:92/00:00:6c:00:00/e0 tag 0 dma 4096 in res 51/40:00:4e:1c:92/00:00:6c:00:00/00 Emask 0x9 (media error) ata7.01: status: { DRDY ERR } ata7.01: error: { UNC } ata7.01: configured for UDMA/100 ata7: EH complete How do I tell what disk this is complaining about? Is there a way to determine what ata7.01 maps to in terms of /dev/sd# values? /proc/scsi/scsi doesn't obviously match scsi# numbers to ata# numbers :-( -- rgds Stephen

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Hibernating a laptop with the power button (Thinkpax X31) under CentOS 5.4
by Robert Heller 29 Jan '10

29 Jan '10

I am having a weird problem trying to get hibernation to work when I press the power button on my Thinkpad X31 under CentOS 5.4. I've modified /etc/acpi/events/power.conf to contain: # ACPID config to power down machine if powerbutton is pressed, but only if # no gnome-power-manager is running event=button/power.* action=/bin/ps awwux | /bin/grep gnome-power-manager | /bin/grep -qv grep || /sbin/shutdown -h now And restarted acpid (sudo /sbin/service acpid restart). I don't run gnome, so there won't be a gnome-power-manager process running. When I press the power button nothing happens (acpid does log that it ran the above action). If I run the action line above in a shell (as root), the machine does hibernate just fine. What is going on here? -- Robert Heller -- 978-544-6933 Deepwoods Software -- Download the Model Railroad System http://www.deepsoft.com/ -- Binaries for Linux and MS-Windows heller(a)deepsoft.com -- http://www.deepsoft.com/ModelRailroadSystem/

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Centos/Linux Disk Caching, might be OT in some ways
by Noob Centos Admin 29 Jan '10

29 Jan '10

I'm trying to optimize some database app running on a CentOS server and wanted to confirm some things about the disk/file caching mechanism. >From what I've read, Linux has a Virtual Filesystem layer that sits between the physical file system and everything else. So no matter what FS is used, applications are still addressing the VFS. Due to this, disk caching is done on an inode/block basis. I'm assuming that this is still the case in CentOS or am I badly mistaken? If that is correct, then here is my scenario and hypothesis. Assuming the server has xxx MB of free memory and the database consist of several tables more than xxx MB in size. So no table will fit entirely into memory. And assuming other processes do not interfere with the caching behaviour or available memory etc. Given the inode caching behaviour, if the DBMS only access a bunch of inodes that total less than xxx MB, is it therefore likely to be always using the cache, hence faster? My thought is that if this is the case, then I could likely speed up the application behaviour if I further split the tables into parts that are more frequently accessed, and parts that are unlikely touched. e.g. the table may currently have rows with 20 fields and total 1KB/row, but very often say only 5/20 fields are used in actual processing. Reading x rows from this table may access x inodes which would not fit into the cache/memory. However if now I break the table into two parts with those 5 fields into a smaller table, there would be a speed increase since the reading the same x rows from this table would only access 1/x inodes. Further more, these would more likely fit into the disk/memory cache for even faster access. Or would I simply be duplicating what the DBMS's index files would already be doing and therefore see no improvement?

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Discuss January 2010