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	<title>TuXHaT&#187; Linux Archives  &#8211; Blog Title</title>
	<atom:link href="http://www.tuxhat.com/category/linux/feed/" rel="self" type="application/rss+xml" />
	<link>http://www.tuxhat.com</link>
	<description>Linux / sysadmin / Debian / Ubuntu / Red Hat / Centos</description>
	<lastBuildDate>Tue, 13 Oct 2009 07:25:21 +0000</lastBuildDate>
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			<item>
		<title>selinux denials on 3ware RAID SMART check</title>
		<link>http://www.tuxhat.com/linux/selinux-denials-and-smartd-in-linux/</link>
		<comments>http://www.tuxhat.com/linux/selinux-denials-and-smartd-in-linux/#comments</comments>
		<pubDate>Fri, 04 Sep 2009 10:02:40 +0000</pubDate>
		<dc:creator>tux</dc:creator>
				<category><![CDATA[Linux]]></category>
		<category><![CDATA[Selinux]]></category>
		<category><![CDATA[Storage]]></category>
		<category><![CDATA[3ware RAID]]></category>
		<category><![CDATA[SMART]]></category>
		<category><![CDATA[smartd]]></category>

		<guid isPermaLink="false">http://www.tuxhat.com/?p=54</guid>
		<description><![CDATA[  If you have a selinux enabled linux machine and is using smartd to check hard drives connected to 3ware RAID controller, you may encounter with couple of denials as below,
 kernel: type=1400 audit(1252046658.420:122): avc:  denied  { ioctl } for  pid=28988 comm=&#8221;smartd&#8221; path=&#8221;/dev/twa0&#8243; dev=tmpfs ino=7729 scontext=root:system_r:fsdaemon_t:s0 tcontext=system_u:object_r:device_t:s0 tclass=chr_file
kernel: type=1400 audit(1252049165.256:123): avc: [...]]]></description>
			<content:encoded><![CDATA[<p>  If you have a selinux enabled linux machine and is using smartd to check hard drives connected to 3ware RAID controller, you may encounter with couple of denials as below,</p>
<p> kernel: type=1400 audit(1252046658.420:122): avc:  denied  { ioctl } for  pid=28988 comm=&#8221;smartd&#8221; path=&#8221;/dev/twa0&#8243; dev=tmpfs ino=7729 scontext=root:system_r:fsdaemon_t:s0 tcontext=system_u:object_r:device_t:s0 tclass=chr_file</p>
<p>kernel: type=1400 audit(1252049165.256:123): avc:  denied  { getattr } for  pid=18264 comm=&#8221;smartd&#8221; path=&#8221;/dev/twa0&#8243; dev=tmpfs ino=7729 scontext=user_u:system_r:fsdaemon_t:s0 tcontext=system_u:object_r:device_t:s0 tclass=chr_file</p>
<p> kernel: type=1400 audit(1252049165.258:124): avc:  denied  { read } for  pid=18264 comm=&#8221;smartd&#8221; name=&#8221;twa0&#8243; dev=tmpfs ino=7729 scontext=user_u:system_r:fsdaemon_t:s0 tcontext=system_u:object_r:device_t:s0 tclass=chr_file</p>
<p> kernel: type=1400 audit(1252049165.258:125): avc:  denied  { ioctl } for  pid=18264 comm=&#8221;smartd&#8221; path=&#8221;/dev/twa0&#8243; dev=tmpfs ino=7729 scontext=user_u:system_r:fsdaemon_t:s0 tcontext=system_u:object_r:device_t:s0 tclass=chr_file</p>
<p> For default the 3ware RAID controller device /dev/twa0 will be having generic filecontext for /dev which is device_t. But smartd runs under context fsdaemon_t, which do not have access to object type device_t.</p>
<p>  So you need to relabel /dev/twa0 as below,</p>
<pre>chcon -t fixed_disk_device_t /dev/twa*</pre>
<p>Conclusion:</p>
<p> fsdaemon_t can operate on object types fixed_disk_device_t</p>
]]></content:encoded>
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		</item>
		<item>
		<title>SMART check for 3ware RAID drives</title>
		<link>http://www.tuxhat.com/linux/smart-check-on-3ware-raid/</link>
		<comments>http://www.tuxhat.com/linux/smart-check-on-3ware-raid/#comments</comments>
		<pubDate>Fri, 04 Sep 2009 09:44:33 +0000</pubDate>
		<dc:creator>tux</dc:creator>
				<category><![CDATA[Linux]]></category>
		<category><![CDATA[Storage]]></category>
		<category><![CDATA[3ware RAID]]></category>
		<category><![CDATA[SMART]]></category>
		<category><![CDATA[tw_cli]]></category>

		<guid isPermaLink="false">http://www.tuxhat.com/?p=49</guid>
		<description><![CDATA[    SMART checks can be performed on hard drives connected to 3ware RAID controllers. The RAID device will be identified as /dev/twa0-15 or /dev/twe0-15 depending on the controller you are using. Each controller will be having ports on to which the hard drives will be connected. For eg: p0 , p1 , [...]]]></description>
			<content:encoded><![CDATA[<p>    SMART checks can be performed on hard drives connected to 3ware RAID controllers. The RAID device will be identified as /dev/twa0-15 or /dev/twe0-15 depending on the controller you are using. Each controller will be having ports on to which the hard drives will be connected. For eg: p0 , p1 , p2 etc.</p>
<p> You may use tw_cli command line utility provided by 3ware to identify the ports on which hard drives are connected.</p>
<pre>
tw_cli /c0/u0 show
</pre>
<p> Above will give details of RAID configuration for unit 0 (u0) on 3ware RAID controller 0 (c0).</p>
<p> Once you got the information on ports , you may do SMART checks on your hard drives as below,</p>
<pre>
smartctl -H -d 3ware,0 /dev/twa0
</pre>
<p>=== START OF READ SMART DATA SECTION ===<br />
SMART overall-health self-assessment test result: PASSED</p>
<p> Here &#8216;-d 3ware,0&#8242; denotes hard drive connected  to port 0. Similarly port 1, port 2 etc. can be checked.</p>
]]></content:encoded>
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		</item>
		<item>
		<title>Troubleshooting selinux</title>
		<link>http://www.tuxhat.com/linux/troubleshooting-selinux/</link>
		<comments>http://www.tuxhat.com/linux/troubleshooting-selinux/#comments</comments>
		<pubDate>Fri, 19 Jun 2009 06:45:37 +0000</pubDate>
		<dc:creator>tux</dc:creator>
				<category><![CDATA[Linux]]></category>
		<category><![CDATA[Selinux]]></category>
		<category><![CDATA[centos 5]]></category>
		<category><![CDATA[selinux for production]]></category>
		<category><![CDATA[selinux on centos5]]></category>

		<guid isPermaLink="false">http://www.tuxhat.com/?p=36</guid>
		<description><![CDATA[I have been recently working on Selinux. It was way invented on 1970&#8217;s, but it is getting great acceptance as a user space security standard these days.
So I was implementing selinux for my production servers,  I can&#8217;t go directly with enforcing mode. But stay with permissive mode and watch avc denials from selinux and [...]]]></description>
			<content:encoded><![CDATA[<p>I have been recently working on Selinux. It was way invented on 1970&#8217;s, but it is getting great acceptance as a user space security standard these days.</p>
<p>So I was implementing selinux for my production servers,  I can&#8217;t go directly with enforcing mode. But stay with permissive mode and watch avc denials from selinux and justify it for it to be allowed / denied. The tiering thing is you need to go through each and every selinux denials from the kernel log facility in syslog. More over one type of denial will be repeated thousands time a day. So I thought of a simple script to unique the duplicate denials. Please see below,</p>
<p>Usage :  avc_uniquer.sh &lt;file containing selinux denials&gt;</p>
<p>avc_uniquer.sh</p>

<div class="wp_syntax"><div class="code"><pre class="bash" style="font-family:monospace;color: #FCFFBA;"><span style="color: #000000; font-weight: bold;color: #B83A24;">for</span> n <span style="color: #000000; font-weight: bold;color: #B83A24;">in</span> <span style="color: #000000; font-weight: bold;color: #CCC;">`</span><span style="color: #c20cb9; font-weight: bold;color: #577A61;">cat</span> <span style="color: #660033;">-n</span> $<span style="color: #000000;color: #DDD;">1</span> <span style="color: #000000; font-weight: bold;color: #CCC;">|</span> <span style="color: #c20cb9; font-weight: bold;color: #577A61;">sed</span>  <span style="color: #ff0000;">'s/\(\ *[[:digit:]]\{1,\}\ *\)\(.*\)\({.*}\)\(.*\)\(scontext.*\)/\1\ \3\ \5/; '</span><span style="color: #000000; font-weight: bold;color: #CCC;">|</span><span style="color: #c20cb9; font-weight: bold;color: #577A61;">sort</span> -k3<span style="color: #000000; font-weight: bold;color: #CCC;">|</span><span style="color: #c20cb9; font-weight: bold;color: #577A61;">uniq</span> <span style="color: #660033;">-f</span> <span style="color: #000000;color: #DDD;">2</span><span style="color: #000000; font-weight: bold;color: #CCC;">|</span><span style="color: #c20cb9; font-weight: bold;color: #577A61;">awk</span> <span style="color: #7a0874; font-weight: bold;color: #CCC;">&#123;</span><span style="color: #ff0000;">'print $1'</span><span style="color: #7a0874; font-weight: bold;color: #CCC;">&#125;</span><span style="color: #000000; font-weight: bold;color: #CCC;">`</span>;
<span style="color: #000000; font-weight: bold;color: #B83A24;">do</span>
<span style="color: #c20cb9; font-weight: bold;color: #577A61;">sed</span> <span style="color: #660033;">-n</span> <span style="color: #ff0000;color: #666666;">&quot;<span style="color: #007800;">$n</span> p&quot;</span> $<span style="color: #000000;color: #DDD;">1</span>;
<span style="color: #000000; font-weight: bold;color: #B83A24;">done</span></pre></div></div>

<p>TIP1:</p>
<pre>
avc_uniquer.sh &lt;filename&gt;|audit2allow
</pre>
<p>The above will give you the selinux rules corresponding to the denials.</p>
<p>Eg:</p>
<pre>Tue Jul 21 11:11:39 IST 2009$avc_uniquer.sh selinux_denial |audit2allow
allow smbd_t httpd_sys_content_t:dir { add_name create write };
allow smbd_t httpd_sys_content_t:file { create getattr lock read write };</pre>
<p>Hope it will be helpful for some <img src='http://www.tuxhat.com/wp-includes/images/smilies/icon_smile.gif' alt=':)' class='wp-smiley' /> </p>
]]></content:encoded>
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		</item>
		<item>
		<title>How to configure Reliance netconnect Broadband+ EVDO connection on linux</title>
		<link>http://www.tuxhat.com/linux/reliance-netconnect-broadband-on-linux/</link>
		<comments>http://www.tuxhat.com/linux/reliance-netconnect-broadband-on-linux/#comments</comments>
		<pubDate>Thu, 09 Apr 2009 19:01:30 +0000</pubDate>
		<dc:creator>tux</dc:creator>
				<category><![CDATA[Fedora]]></category>
		<category><![CDATA[Linux]]></category>
		<category><![CDATA[Broadand wireless internet in india on linux]]></category>
		<category><![CDATA[EVDO]]></category>
		<category><![CDATA[Reliance]]></category>
		<category><![CDATA[Reliance EVDO broadband connection]]></category>
		<category><![CDATA[Reliance netconnect Broadband+ on linux]]></category>

		<guid isPermaLink="false">http://www.tuxhat.com/?p=24</guid>
		<description><![CDATA[I recently started using Reliance netconnect Broadband+ EVDO connection on linux. I didn&#8217;t find exact help on how to get the EVDO modem ( ZTE AC8710) working on linux. So I thought of sharing the procedure,

The above picture shows the ZTE AC8710 modem I got along with my connection. It&#8217;s pretty easy to install it [...]]]></description>
			<content:encoded><![CDATA[<p>I recently started using Reliance netconnect Broadband+ EVDO connection on linux. I didn&#8217;t find exact help on how to get the EVDO modem ( ZTE AC8710) working on linux. So I thought of sharing the procedure,</p>
<p><img class="aligncenter size-medium wp-image-25" title="ZTE AC8710 EVDO Modem" src="http://www.tuxhat.com/wp-content/uploads/2009/04/zte_ac8710-300x225.jpg" alt="ZTE AC8710 EVDO Modem" width="300" height="225" /></p>
<p>The above picture shows the ZTE AC8710 modem I got along with my connection. It&#8217;s pretty easy to install it in windows, you even do not need to have the driver CD. Just plug in the modem, at first it will be detected as a storage device. The storage device have the modem driver built into it, so an autoplay will install the modem driver and reliance net connecting suite on to your windows.</p>
<p>The feature of USB devices to have multiple configuration (storage device / modem) can cause hell lot of confusions, while using it in linux. Let me explain,</p>
<p>First I inserted my USB modem on to the port in Fedora 10 installed box, below is the kernel message and command  output of &#8216;lsusb&#8217; ,</p>
<pre>
======= Kernel message ====

usb 3-1: new full speed USB device using uhci_hcd and address 7
usb 3-1: New USB device found, idVendor=19d2, idProduct=fff6
usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 3-1: Product: USB Storage
usb 3-1: Manufacturer: ZTE, Incorporated
usb 3-1: SerialNumber: 000000000002
usb 3-1: configuration #1 chosen from 1 choice
scsi6 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 7
usb-storage: waiting for device to settle before scanning
usb-storage: device scan complete
scsi 6:0:0:0: CD-ROM            ZTE      USB Storage FFF1 2.31 PQ: 0 ANSI: 2
sr1: scsi-1 drive
sr 6:0:0:0: Attached scsi CD-ROM sr1
sr 6:0:0:0: Attached scsi generic sg3 type 5
sr1: CDROM (ioctl) error, command: Get configuration 46 00 00 00 00 00 00 00 20 00
sr: Sense Key : No Sense [current]
sr: Add. Sense: No additional sense information
</pre>
<pre>
===== lsusb =======

[root@localhost win]# lsusb
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 009: ID 19d2:fff6 ONDA Communication S.p.A.
Bus 003 Device 006: ID 1058:0704 Western Digital Technologies, Inc.
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
[root@localhost win]#
</pre>
<p>The kernel message says, it detected the modem as a storage device. Exactly as a SCSI cdrom device /dev/sr1. The lsusb output gives the device id and vendor id as 19d2 and fff6 respectively.  Mean my fedora 10 box was able to detect configuration 1 (storage) but not configuration 2 ( Modem ) of the USB device.</p>
<p>I was quite sure that I do not have the device driver required to detect the modem in my list of kernel modules. After some search, I found the kernel module &#8216;usbserial.ko&#8217; which is needed to make the modem ZTE AC8710 work.</p>
<p>Luckily, before trying usbserial I found linux device driver pack for BSNL EVDO connection from the homepage of the USB modem provider. Locate it here,</p>
<p><strong>http://www.ztemt.com.cn/ennewzte/service/ziliao.action</strong></p>
<p>The driver from the above link is for ZTE AC8700 and  not AC8710, still I made up my mind to try. The driver pack consists below files,</p>
<p>ztemtEVDO-1.1-8-i386-ubuntu804.deb<br />
ztemtEVDO-1.1-8.i586-fedora9.rpm<br />
ztemtEVDO-1.1-8.i586-suse103.rpm</p>
<p>I choose fedora9 for my fedora10 installation, the installation went fine. The installation adds a service named &#8221;ztemtvcdromd&#8221; to your runlevel. What does service ztemtvcdromd do ?</p>
<p>* Installs udev rules needed to detect the USB EVDO modem</p>
<p>* Inserts USB module ztemt.ko</p>
<p>* Starts the process /usr/sbin/ztemtvcdromd</p>
<p>I started the service all worked well, except the loading of the kernel module ztemt.ko. I found that ztemt.ko was not  compiled for my version of kernel 2.6.29.</p>
<p>Replugged the modem. Once again I went through the kernel messages and lsusb output. To my surprise I found my product id changed from 0xfff6 to 0xfff1 with below messages from kernel,</p>
<pre>
======= Kernel message ====

usb 3-1: new full speed USB device using uhci_hcd and address 8
usb 3-1: New USB device found, idVendor=19d2, idProduct=fff6
usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 3-1: Product: USB Storage
usb 3-1: Manufacturer: ZTE, Incorporated
usb 3-1: SerialNumber: 000000000002
usb 3-1: configuration #1 chosen from 1 choice
scsi7 : SCSI emulation for USB Mass Storage devices
usb-storage: device found at 8
usb-storage: waiting for device to settle before scanning
usb-storage: device scan complete
scsi 7:0:0:0: CD-ROM            ZTE      USB Storage FFF1 2.31 PQ: 0 ANSI: 2
sr1: scsi-1 drive
sr 7:0:0:0: Attached scsi CD-ROM sr1
sr 7:0:0:0: Attached scsi generic sg3 type 5
usb 3-1: USB disconnect, address 8
usb 3-1: new full speed USB device using uhci_hcd and address 9
usb 3-1: New USB device found, idVendor=19d2, idProduct=fff1
usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
usb 3-1: Product: ZTE CDMA Tech
usb 3-1: Manufacturer: ZTE, Incorporated
usb 3-1: configuration #1 chosen from 1 choice
</pre>
<pre>
===== lsusb =======

[root@localhost ztemtEVDO]# lsusb
Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 003 Device 009: ID 19d2:fff1 ONDA Communication S.p.A.
Bus 003 Device 006: ID 1058:0704 Western Digital Technologies, Inc.
Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
[root@localhost ztemtEVDO]#
</pre>
<p>The kernel was now able to detect the second USB configuration of the device with vendor id 0&#215;19d2 and 0xfff1, which is suppose our CDMA modem. Now the final thing to be done is load the kernel module ztemt.ko. I found the source code for the kernel module in the following location, which came along with the driver package provided by the vendor,</p>
<p>/usr/local/bin/ztemtEVDO/usb-serial.tar.gz</p>
<p>I recompiled it for my version of kernel (2.6.29) and loaded ztemt.ko. Again replugged the USB modem. But couldn&#8217;t find the device getting registered in /dev. So  I went through the source code of ztemt.ko and found it similar to native driver provided by the linux kernel for USB serial modems (usbserial.ko)</p>
<p>So I decided to go with usbserial.ko,</p>
<p>* Restarted the service ztemtvcdromd</p>
<p>* Ensured that the driver ztemt.ko is not loaded</p>
<p>* Took vendor id and device id from lsusb output, which is 19d2:fff1 for me.</p>
<p>* Executed command &#8216;modprobe usbserial vendor=0&#215;19d2 product=0xfff1&#8242;</p>
<p>Now I got the below kernel message,</p>
<pre>
usbserial_generic 3-1:1.0: generic converter detected
usb 3-1: generic converter now attached to ttyUSB0
usbserial_generic 3-1:1.1: generic converter detected
usb 3-1: generic converter now attached to ttyUSB1
usbserial_generic 3-1:1.2: generic converter detected
usb 3-1: generic converter now attached to ttyUSB2
usbserial_generic 3-1:1.3: generic converter detected
usb 3-1: generic converter now attached to ttyUSB3
usbserial_generic 3-1:1.4: generic converter detected
usb 3-1: generic converter now attached to ttyUSB4
</pre>
<p>It shows that my modem is registered as /dev/ttyUSB0, success!!</p>
<p>I wrote below wvdial script in /etc/wvdial.conf,</p>
<pre>
[Dialer Defaults]
Init2 = ATQ0 V1 E1 S0=0 &amp;C1 &amp;D2 +FCLASS=0
Modem Type = Analog Modem
ISDN = 0
Username = xxxxxx # Your 10 digit phone number
Init1 = ATZ
Password = xxxxxxx # Your 10 digit phone number
Modem = /dev/ttyUSB0
Baud = 3686400
Phone = #777
stupid mode = 1
</pre>
<p>Now it is all set to establish the connection, executed command &#8216;wvdial&#8217; as root. I got connected to the internet Hurrreh!!,</p>
<pre>
--&gt; WvDial: Internet dialer version 1.60
--&gt; Cannot get information for serial port.
--&gt; Initializing modem.
--&gt; Sending: ATZ
ATZ
OK
--&gt; Sending: ATQ0 V1 E1 S0=0 &amp;C1 &amp;D2 +FCLASS=0
ATQ0 V1 E1 S0=0 &amp;C1 &amp;D2 +FCLASS=0
OK
--&gt; Modem initialized.
--&gt; Sending: ATDT#777
--&gt; Waiting for carrier.
ATDT#777
CONNECT
--&gt; Carrier detected.  Starting PPP immediately.
--&gt; Starting pppd at Thu Apr  9 11:45:27 2009
--&gt; Pid of pppd: 9389
--&gt; Using interface ppp0
--&gt; local  IP address 115.240.95.59
--&gt; remote IP address 220.224.141.129
--&gt; primary   DNS address 202.138.97.193
--&gt; secondary DNS address 202.138.96.2
</pre>
<p>Now copy your primary and secondary nameservers to /etc/resolv.conf,</p>
<pre>
[root@localhost ztemtEVDO]# cat /etc/resolv.conf
nameserver 202.138.96.2
nameserver 202.138.97.193
</pre>
<p>Now try any browser and access your websites or download with Reliance netconnect broadband+ EVDO connection <img src='http://www.tuxhat.com/wp-includes/images/smilies/icon_smile.gif' alt=':)' class='wp-smiley' />   On an average I got 60kBps download speed.</p>
<p>Later on I edited service script /etc/init.d/ztemtvcdromd to remove &#8216;/sbin/modprobe ztemt.ko&#8217; and &#8216;/sbin/rmmod ztemt.ko&#8217; from start and stop cases respectively. Then added lines &#8216;/sbin/modprobe usbserial vendor=0&#215;19d2 product=0xfff1&#8242; and &#8216;/sbin/rmmod usbserial&#8217;   to start and stop cases respectively.</p>
<p>FYI:  Product ID may differ in your case, so be careful in noting it down from &#8216;dmesg&#8217; or &#8216;lsusb&#8217; output.</p>
<p>Issues detected:</p>
<p>Reconnecting second time to internet doesn&#8217;t work once you disconnect your connection by using Ctrl-C to wvdial. Re-inserting the modem to USB port will solve it <img src='http://www.tuxhat.com/wp-includes/images/smilies/icon_smile.gif' alt=':)' class='wp-smiley' /> </p>
<p>Contact: asalamr@gmail.com</p>
]]></content:encoded>
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		</item>
		<item>
		<title>How to setup local yum repository for centos 5 media</title>
		<link>http://www.tuxhat.com/linux/centos/setup-local-yum-repository-centos-5-media/</link>
		<comments>http://www.tuxhat.com/linux/centos/setup-local-yum-repository-centos-5-media/#comments</comments>
		<pubDate>Tue, 10 Mar 2009 18:30:25 +0000</pubDate>
		<dc:creator>tux</dc:creator>
				<category><![CDATA[centos]]></category>
		<category><![CDATA[c5-media]]></category>
		<category><![CDATA[centos 5]]></category>
		<category><![CDATA[yum]]></category>
		<category><![CDATA[yum repository]]></category>

		<guid isPermaLink="false">http://www.tuxhat.com/?p=16</guid>
		<description><![CDATA[setting up local yum repository for centos 5 media]]></description>
			<content:encoded><![CDATA[<p>You should already have /etc/yum.repos.d/CentOS-Media.repo after installing centos. If you don&#8217;t have one create  as below,</p>
<p>[c5-media]<br />
name=CentOS-$releasever &#8211; Media<br />
baseurl=file:///media/CentOS/<br />
file:///media/cdrom/<br />
file:///media/cdrecorder/<br />
enabled=0</p>
<p>Then mount your cdrom to either /media/CentOS/ |  /media/cdrom/ | /media/cdrecorder/,</p>
<p>mount /dev/cdrom /media/cdrom</p>
<p>So now your yum repository for centos5  is readyat /media/cdrom.</p>
<p>To install a package from the centos media repository created,</p>
<p>yum &#8211;disablerepo=\* &#8211;enablerepo=c5-media install &lt;package name&gt;</p>
<p>By default the repositry named  c5-media here will be disabled as enabled=0 is given in /etc/yum.repos.d/CentOS-Media.repo. The above command will disable all other repositries and enable the c5-media alone.</p>
<p>Enjoy installing <img src='http://www.tuxhat.com/wp-includes/images/smilies/icon_smile.gif' alt=':)' class='wp-smiley' /> </p>
]]></content:encoded>
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		<title>remove pulse audio from fedora 9</title>
		<link>http://www.tuxhat.com/linux/fedora/remove-pulse-audio-from-fedora-9/</link>
		<comments>http://www.tuxhat.com/linux/fedora/remove-pulse-audio-from-fedora-9/#comments</comments>
		<pubDate>Mon, 02 Mar 2009 17:36:00 +0000</pubDate>
		<dc:creator>tux</dc:creator>
				<category><![CDATA[Fedora]]></category>
		<category><![CDATA[ALSA]]></category>
		<category><![CDATA[fedora 9]]></category>
		<category><![CDATA[pulse audio]]></category>

		<guid isPermaLink="false">http://www.tuxhat.com/?p=6</guid>
		<description><![CDATA[Pulse audio is still buggy in fedora 9, so don&#8217;t use it. Problems encountered,
* No simultaneous access to the dsp device  
* When switching from X to tty background audio crashes
So remove pulse audio and fall back to ALSA,
 yum remove  pulseaudio alsa-plugins-pulseaudio
]]></description>
			<content:encoded><![CDATA[<p>Pulse audio is still buggy in fedora 9, so don&#8217;t use it. Problems encountered,</p>
<p>* No simultaneous access to the dsp device <img src='http://www.tuxhat.com/wp-includes/images/smilies/icon_sad.gif' alt=':(' class='wp-smiley' /> </p>
<p>* When switching from X to tty background audio crashes</p>
<p>So remove pulse audio and fall back to ALSA,</p>
<p><strong> yum remove  pulseaudio alsa-plugins-pulseaudio</strong></p>
]]></content:encoded>
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		<item>
		<title>Ext 4 filesystem stable released with linux-2.6.28</title>
		<link>http://www.tuxhat.com/linux/filesystem/ext-4-filesystem-stable-released-with-linux-2628/</link>
		<comments>http://www.tuxhat.com/linux/filesystem/ext-4-filesystem-stable-released-with-linux-2628/#comments</comments>
		<pubDate>Mon, 02 Mar 2009 13:38:12 +0000</pubDate>
		<dc:creator>tux</dc:creator>
				<category><![CDATA[Filesystem]]></category>
		<category><![CDATA[ext4]]></category>
		<category><![CDATA[linux 2.6.28]]></category>

		<guid isPermaLink="false">http://www.tuxhat.com/?p=3</guid>
		<description><![CDATA[

All should be well set to go ahead with migrating to ext4 filesystem, as stable version of ext4 is out with the latest linux kernel 2.6.28. Unlike ext2 to ext3, which was all about adding journaling feature to ext2, ext4 had lot of improvements.
Ext3 &#8211; 16 TB of maximum filesystem size, and 2 TB of [...]]]></description>
			<content:encoded><![CDATA[<div class="entry">
<div class="entry">
<p>All should be well set to go ahead with migrating to ext4 filesystem, as stable version of ext4 is out with the latest linux kernel 2.6.28. Unlike ext2 to ext3, which was all about adding journaling feature to ext2, ext4 had lot of improvements.</p>
<p>Ext3 &#8211; 16 TB of maximum filesystem size, and 2 TB of maximum file size.<br />
Number of subdirectories contained in a single directory in Ext3 is 32.000.</p>
<p>Ext4 adds 48-bit block addressing, so it will have 1 EB of maximum filesystem size and 16 TB of maximum file size. 1 EB = 1,048,576 TB (1 EB = 1024 PB, 1 PB = 1024 TB, 1 TB = 1024 GB).</p>
<p>Ext4 breaks that limit and allows a unlimited number of subdirectories.</p>
<p>Introduction of extends (Instead of indirect mapping of each and every blocks used by a file in ext3, ext4 produces ‘extents’ which says the data blocks of a file are in next ‘n’ blocks, mean a 200 MB file can be stored across a bunch of contiguous blocks ) in ext4 is set to bring a drastic performance upgrade and reduce fragmentation.</p>
<p>Unlike ext3, which can allocate only one block at a time, ext4 comes up with multi block allocator. (mballoc). This reduces disk allocation time greatly in ext4.</p>
<p>Delayed allocation functionality of ext4 will prevent excessive work done. In ext3, when a write function call is made for a 10MB file, it immediately starts allocating the 10MB even if the data is going t Delayed allocation functionality of ext4 will prevent excessive work done. In ext3, when a write function call is made for a 10MB file, it immediately starts allocating the 10MB even if the data is going to be in cache before it actually gets written to the disk. Where as ext4 only allocates disk space when actually the data gets written from cache to disk. This functionality works well with the above said extends and multiblock allocation features.o be in cache before it actually gets written to the disk. Where as ext4 only allocates disk space when actually the data gets written from cache to disk. This functionality works well with the above said extends and multiblock allocation features.</p>
<p>Next amazing thing about ext4 is the reduced fsck time needed ~ 2 to 20 times… whoo… This is made possible by writing a list of unused inodes at the end of each inode group table, so fsck can skip those inodes from checking. The free inode list is created by fsck when its ran first at the first time on the filesystem, from the very next fsck you will have the advantage of reduced checking time.</p>
<p>Journal checksumming is another important feature introduced in ext4, which writes and stores checksums of filesystem journal. This speeds up ext4 20% compared to its predecessor ext3 by omitting two phase commit system.</p>
<p>Online defragmentation is set to be live in future releases of linux kernel which supports a tool named e4defrag, which do defragmentation of ext4 filesystems.</p>
<p>inode related features,</p>
<p>* Larger inodes for accommodating nano time stamps, inode reservation.<br />
* nano timestamps for files<br />
* Inode reservation, when a directory is created some inodes are created in advance for faster performance.<br />
* faster extended attributes</p>
<p>Persistent preallocation</p>
<p>Barriers on by default</p>
<p>Migrating from ext3 to ext4</p>
<p>You need to use the tune2fs and fsck tools in the filesystem, and that filesystem needs to be unmounted. Run:</p>
<p>tune2fs -O extents,uninit_bg,dir_index /dev/yourfilesystem</p></div>
</div>
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