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Slightly OT: First Time KVM and LVM on Centos
by Jeff Boyce 21 Jun '11

21 Jun '11

Greetings - I am a novice system administrator and will soon be purchasing a new server to replacing an aging file server for my company. I am considering setting up the new server as a KVM host with two guests; one guest as the Samba file server and a second guest as a testing area. My old server was set up about 7 years ago and has a 5 disk raid 5 configuration without LVM. I understand the benefits of using LVM and KVM in the right circumstances, but have never used either of them. I have spent a couple of days over the last week trying to understand how to setup a KVM host with guests, but there is an area that I still don't understand; that is the relationship between the underlying raid partitions, LVM, and allocating space to a host and guests. Many of the standard search term combinations in Google don't seem to be getting me anywhere. From what I have read so far I think that I want to have my file server guest using a raw partition rather than an image file, but I haven't found anything with examples or best-practices guidance for partitioning or volume management with hosts and guest VMs. So I am hoping that someone here can give me some pointers, or point me to some clear how-to's somewhere. Any help is appreciated. Thanks. Jeff Boyce Meridian Environmental www.meridianenv.com

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lots of disk activity keep process from responding
by Jerry Geis 20 Jun '11

20 Jun '11

hi all I have something like 3000 log files in a directory (from data collection). At 4am in the morning cron runs a script of mine that essentiallly trims all files in that directory back to a certain size. Basically does a "tail -c XXXX filename > tmp_filename" I have noticed that only around the 4am-4:15 time frame when the trim is happening does my other process log connection attempts but my process (forking and opening databases) is not responding in time to give data back to the connecting process. Not critically important as it just tries again and all ok... My question is how do I tell the script that runs to run at a lower priority perhaps ??? Or is there another way to do this I am not aware of? The trimmming of the log files is just so they they dont take a bunch of space on the HD. It doesnt have to be done supper fast or anything. Any ideas I might try? Thanks, Jerry

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Re: [CentOS] Config file semantics.
by m.roth＠5-cent.us 18 Jun '11

18 Jun '11

Devin Reade wrote: > --On Friday, June 17, 2011 02:27:22 PM -0400 m.roth(a)5-cent.us wrote: > >> Minkowski space? > > Sure. I'll implement M-x minkowski-space-mode as soon as I > get 'elsewhere' (in Minkowski terms, that is). > You're sure that's not a vim option? mark Kirk: Warp 5, Scotty! Scotty: We're shovelin' as fast as we can, captain! Goddamn dnsorbs! Two bounces....

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non-fluff: NIC configuration: mingnt?
by m.roth＠5-cent.us 17 Jun '11

17 Jun '11

We've got this really bizarre problem, trying to get a bridge/firewall working. My manager and I are almost grasping at straws.... Anyway, I'm using lshw to look at an identical machine, and a Dell 1950 that works when configured as a bridge, and there's one thing I don't know: does anyone know what mingnt is? Thanks. mark

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Config file semantics.
by Mike A. Harris 17 Jun '11

17 Jun '11

Personally, I find that indenting config files by 3 spaces has a lot of advantages to indenting them by 4 spaces although conventional wisdom might suggest otherwise. Who's with me on this?

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athentication service
by nabi 17 Jun '11

17 Jun '11

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Odd issue with custom udev rule at boot
by James A. Peltier 16 Jun '11

16 Jun '11

Hi All, I've written a custom udev rule to change the permissions of /dev/ttyS* but it doesn't seem to be working at boot up. If I run /sbin/udevcontrol reload_rules; udevtrigger The rules are parsed, applied and the permissions are then correct but why is it not doing so at boot? The file in questions I've called /etc/udev/rules.d/49-udev-override.rules and it contains KERNEL=="tty[A-Z]*", NAME="%k", GROUP="rcl", MODE="0660", OPTIONS="last_rule" the default 50-udev.rules file has been left untouched. SELinux is in permissive mode and so I can't find a reason why it is happening. Anyone have any ideas? -- James A. Peltier IT Services - Research Computing Group Simon Fraser University - Burnaby Campus Phone : 778-782-6573 Fax : 778-782-3045 E-Mail : jpeltier(a)sfu.ca Website : http://www.sfu.ca/itservices http://blogs.sfu.ca/people/jpeltier

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Possible to use multiple disk to bypass I/O wait?
by Emmanuel Noobadmin 16 Jun '11

16 Jun '11

I'm trying to resolve an I/O problem on a CentOS 5.6 server. The process basically scans through Maildirs, checking for space usage and quota. Because there are hundred odd user folders and several 10s of thousands of small files, this sends the I/O wait % way high. The server hits a very high load level and stops responding to other requests until the crawl is done. I am wondering if I add another disk and symlink the sub-directories to that, would that free up the server to respond to other requests despite the wait on that disk? Alternatively, if I mdraid mirror the existing disk, would md be smart enough to read using the other disk while the first's tied up with the first process?

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A bridge problem
by m.roth＠5-cent.us 15 Jun '11

15 Jun '11

We just went to replace the bridge/firewall services one one server with the same on another. It's pretty simple, and I literally cloned (w/ rsync) a third server that does this onto the one that will be the new one. Then copied the /etc/sysconfig/iptables from the one being replaced, and brought it up this morning. Nope. We had to put everything back the way it was. The new one sees the two or three servers behind the firewall, and we can ping them, from the new box. On one, we see IPP broadcasts; in fact, we see lots of broadcast packets using tcpdump. From outside, though, you can't see the servers. Trying to ping them, they see nothing. It seems to be the case that tcp and icmp packets are blocked, and we can't figure out why. CentOS 5.6. ifcfg-eth0 DEVICE=eth0 BRIDGE=br3 BOOTPROTO=dhcp HWADDR=aa:bb:cc:dd:ee:ff ONBOOT=yes ifcfg-eth1 DEVICE=eth1 BRIDGE=br3 HWADDR=aa:bb:cc:dd:ee:gg ONBOOT=yes ifcfg-br3 DEVICE=br3 ONBOOT=yes TYPE=Bridge BOOTPROTO=static IPADDR=<our ip> NETMASK=255.255.254.0 NETWORK=<our nw> GATEWAY=<our gw> Any ideas? mark

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Re: [CentOS] CentOS-announce Digest, Vol 76, Issue 4
by Les Mikesell 15 Jun '11

15 Jun '11

Are the updates supposed to be synced to the mirrors before the announce message goes out? Only a random few machines could get these updates yesterday. Also, is there some reason behind the package name/numbering going from: java-1.6.0-openjdk-1.6.0.0-1.21.b17.el5 to java-1.6.0-openjdk.x86_64 1:1.6.0.0-1.22.1.9.8.el5_6 ? -- Les Mikesell lesmikesell(a)gmail.com

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