Discuss January 2012

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221 discussions

Write to USB pendrives horribly slow
by wwp 12 Jan '12

12 Jan '12

Hello there, since I installed CentOS6 few months ago (kept up-to-date using yum), I'm facing very poor performances when writing to USB pendrives. The hardware: a Dell Latitude E6500 laptop (Intel Core Duo P8600 @2.40Ghz), 4Go RAM + 4Go swap, several USB2 pendrives of various brands (less than old, all formatted as vfat). When I perform a copy (with cp or midnight commander, copying big AVI files between 300Mo to 1.4Go) to those devices, whatever the source is on the same device or on another disk, I notice that the CPU activity shows 2 phases as far as I can see with the Gnome system monitor applet: - a phase where both CPUs show less than 20% of activity, and IOWait is <80%. It lasts the time I would expect such copy to last (say, it's like writing at 1-4MB/sec to such devices, which is reasonable or expected). - a phase, at least twice as long as 1st phase but this ratio depends on the file copy size, where CPUs show <5% of activity but IOWait is at 100%. During phase 1, system and applications are responsive, as expected during a file copy to external USB2 disks. During phase 2, system is slow, applications are often non responsive. I was not facing this behaviour w/ Fedora 11, not w/ the Windows XP system also installed on this laptop. I'm not facing such poor performances when writing to externals SATA drives (thru the same USB2 ports), even formatted as vfat. Neither when writing to those pendrives from another hardware system. `hdparm -tT` is useless here. I wonder if some mount options aren't wrong with USB pendrives, see: /dev/sdd1 on /media/monolith type vfat (rw,nosuid,nodev,uhelper=udisks,shortname=mixed,dmask=0077,utf8=1,flush) my suspicion is about the flush option, which I find atypical here. BTW, I'm still unable to control the mount options that are automatically set by Gnome - even if I can mount manually if I want. Any hint? Regards, -- wwp

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Re: [CentOS] CPU Usage when idle
by sheraz naz 12 Jan '12

12 Jan '12

--- On Wed, 1/11/12, Warren Young <warren(a)etr-usa.com> wrote: From: Warren Young <warren(a)etr-usa.com> Subject: Re: [CentOS] CPU Usage when idle To: "CentOS mailing list" <centos(a)centos.org> Date: Wednesday, January 11, 2012, 8:14 PM On 1/11/2012 6:42 PM, Jorge Fábregas wrote: > > They did a great job with RHEL6 and I'm > curious what was changed in order to accomplish this. It's probably the PowerTop work, primarily done to get better battery life on laptops by throttling the CPU down when it's idle: http://www.lesswatts.org/projects/powertop/ powertop is just tool, similar to top command to see the top programs causing the cpu to wake up. I think the main improvement that Redhat themselves have provided is the use of tickless kernel. RHEL 5 used a periodic timer for each CPU causing it to wake up every few milliseonds to process events and thus never really entering idle state. The tickless kernel in RHEL6 allows the system to enter idle state more often. If you see system consuming too much power, you can install and run powertop to find the offending programs. See section 1.2 in RHEL 6 power management guide. Thanks Sheraz

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SOLVED: Centos6 Installer can handle 3TB Disks with little prepare.
by Marko Weber 12 Jan '12

12 Jan '12

Hi List, yesterday i tried to install CentOS6 on Server bei Hetzner.de I noticed that Anaconda Installer is not possible to handle the 3TB Disks in Server when u try to Partition them. U can do only 3 normal partitions or u can do only 3 raid partitions, the SOLUTION is: Before U install Centos6 on the new naked server: a) Start Server in Rescue mode b) parted /dev/sda c) mklabel gpt ( Answer YES, you will do new disk label ) d) print ( look that all is fine? ) e) parted /dev/sdb f) mklabel gpt ( Answer YES, you will do new disk label ) g) print ( Answer YES, you will do new disk label ) h) q ( for quit ) Now go back to Hetzner Customer Menu, and activate VNC INSTALL Centos6 English 64 Bit Voila! now at the Part of Partitioning u say "CUSTOM LAYOUT" and you can do your own Layout as you like. Maybe this helps other ppl too. Marko ( from cloudy stormy rainy Hamburg Harbour )

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SELinux and access across 'similar types'
by Bennett Haselton 12 Jan '12

12 Jan '12

http://wiki.centos.org/HowTos/SELinux says: "Access is only allowed between similar types, so Apache running as httpd_t can read /var/www/html/index.html of type httpd_sys_content_t." however the doc doesn't define what "similar types" means. I assumed it just meant "beginning with the same prefix". However that can't be right because on my system with SELinux turned on, httpd runs as type init_t: [root@peacefire04 - /root # ps awuxZ | grep httpd | head -n 3 system_u:system_r:init_t:s0 root 2521 0.1 0.4 21680 8820 ? Ss 05:05 0:00 /usr/sbin/httpd system_u:system_r:init_t:s0 apache 2550 0.0 0.4 23364 8920 ? S 05:05 0:00 /usr/sbin/httpd system_u:system_r:init_t:s0 apache 2551 0.1 0.4 22736 8212 ? S 05:05 0:00 /usr/sbin/httpd and the robots.txt file has type file_t: [root@peacefire04 - /root # ls -lZ /var/www/html/robots.txt -rw-rw-rw- root root system_u:object_r:file_t:s0 /var/www/html/robots.txt but Apache can of course access that file. So in Type Enforcement, what determines what process type can access what file type? Bennett

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Re: [CentOS] CentOS post acknowledgement
by Darr247 12 Jan '12

12 Jan '12

Hmmmm... well THAT doesn't seem right - getting 2 post acknowledgements to a single message.

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Re: [CentOS] USB install annoyances
by Darr247 12 Jan '12

12 Jan '12

On Tuesday, January 10, 2012 17:53 [UTC -5], Darr247 spake thusly: > I did not see that synopsis in your original post (and I'm not sure I > could figure out what commands you used by that). > The only 2 replies to this thread I saw in digest 84 issue 9 were to > John Doe. > > Anyway, this is what I have in my notes, though I see you've marked > this as solved... > > mostly assuming sdb as the USB device. > > From blank USB stick to bootable install: > > yum install livecd-tools syslinux > dd if=/dev/zero of=/dev/sdb bs=512 count=1000 > parted /dev/sdb mklabel msdos > parted /dev/sdb mkpartfs p ext2 0% 100% > tune2fs -m0 /dev/sdb1 Oh, and sometimes the tune2fs command isn't needed. If I recall, it's needed only if the stick has never been formatted. > parted /dev/sdb toggle 1 boot > umount /dev/sdb1 > livecd-iso-to-disk <path to>/DVD.iso /dev/sdb1 > > mkdir /mnt/iso > mount -o loop <path to>/DVD.iso /mnt/iso > mkdir media<usb stick>/images > cp /mnt/iso/images/install.img media<usb stick>images > cp <path to>/DVD.iso /media/<usb stick>/ > > TEST: > qemu -m 512 /dev/sdb > > > I guess I should add > yum install qemu > to my notes, as I don't think that's installed by default. > > But using livecd-iso-to-disk makes it NOT ask for the image file > location during the install. Try it. > > Personally, I think they should've named it bootable-iso-tools, but > everyone's probably used to the livecd-tools name by now.

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Re: [CentOS] USB install annoyances
by Darr247 12 Jan '12

12 Jan '12

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CPU Usage when idle
by Jorge Fábregas 12 Jan '12

12 Jan '12

Hello guys, Did anyone noticed how green CentOS 6 is compared to the previous release? I've been running a couple of "CentOS 6" VMs (on our vSphere environment) for the last couple of weeks and noticed a BIG difference when it comes to CPU usage when the VM is completely idle. I would like to share what I've seen in our environment: PfSense 2.0 (FreeBSD) VM: 40 Mhz CentOS 5.7 VM: 60 Mhz CentOS 6.2 VM: 5 Mhz This is really wonderful. They did a great job with RHEL6 and I'm curious what was changed in order to accomplish this. Regards, Jorge

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Building REDHAT Desktop Virtualization Solution With Centos
by Arif Tuhin 12 Jan '12

12 Jan '12

Redhat offers a desktop virtualization solution using "kvm,qemu,libvirt and spice" which is directed at centralized server hosting virtual desktops and thin clients connecting to it. All the relevant software are open source. So it should be possible to achieve the same feat with CentOS. Anyone know any complete tutorial regarding this? I've found separate tutorials regarding spice, kvm etc. But a complete tutorial describing how to emulate the "Redhat virtualization for Desktops" will be very handy. Thanks in advance.

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Centos 5.7, I10 video, 1920x1080 monitor
by Frank Cox 12 Jan '12

12 Jan '12

I have a Centos 5.7 machine with Intel I10 video (built-in, I guess -- this is one of those all-in-one mini terminal things) that I'm trying to put a new 1920x1080 monitor onto, without conspicuous success. Prior to this it's been using a smaller monitor with no issues. Try as I might I can't get the new monitor to run at its 1920x1080 resolution. I just realized that I forgot to write down the actual resolution that it runs at but it's less than it should be, maybe 1280x1024? Obviously the display looks pretty crappy like that. I tried following the instructions posted here: http://www.ubuntugeek.com/how-change-display-resolution-settings-using-xran… but when I got to the step of typing "xrandr --newmode ..." all I got was a help screen for xrandr command line options (and --newmode wasn't listed as one of them). I tried this: system-config-display --reconfig --set-resolution=1920x1080 --set-depth=24 --set-driver=vesa --set-videoram=0 It rewrote the xorg.conf file but I still didn't get 1920x1080. I tried changing "vesa" to "i810" in xorg.conf and was then told that the xserver can't be started. It then took me to a simple GUI-style monitor setup screen and I told it that a 1920x1080 LCD monitor was connected. It then created the following xorg.conf, but I still don't get 1920x1080. The Xorg.0.log file is over 2000 lines so I won't include it in this mesage but I have posted it here: http://www.melvilletheatre.com/Xorg.0.log.bz2 Here is what I currently have for xorg.conf but again, it doesn't give me the full resolution on the monitor: # Xorg configuration created by system-config-display Section "ServerLayout" Identifier "single head configuration" Screen 0 "Screen0" 0 0 InputDevice "Keyboard0" "CoreKeyboard" EndSection Section "InputDevice" Identifier "Keyboard0" Driver "kbd" Option "XkbModel" "pc105" Option "XkbLayout" "us" EndSection Section "Monitor" Identifier "Monitor0" ModelName "LCD Panel 1920x1080" ### Comment all HorizSync and VertSync values to use DDC: HorizSync 31.5 - 67.0 VertRefresh 56.0 - 65.0 Option "dpms" EndSection Section "Device" Identifier "Videocard0" Driver "vesa" EndSection Section "Screen" Identifier "Screen0" Device "Videocard0" Monitor "Monitor0" DefaultDepth 24 SubSection "Display" Viewport 0 0 Depth 24 EndSubSection EndSection -- MELVILLE THEATRE ~ Real D 3D Digital Cinema ~ www.melvilletheatre.com www.creekfm.com - FIFTY THOUSAND WATTS of POW WOW POWER!

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Discuss January 2012