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Centos7 Kernel Panic
by Sachin Gupta 19 Aug '15

19 Aug '15

Hello Everyone, I have prepared following isolinux.cfg. default linux label linux kernel /vmlinuz append initrd=/initrd.gz But kernel panics with the standard message 'Kernel panic - not syncing: No init found'. Linux kernel version is 3.10. I tried to read the init.txt too.But could not figure out the issue. Can you please help me figure out the problem ? Thanks Sachin

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Optimum Block Size to use
by Jatin Davey 19 Aug '15

19 Aug '15

Hi All We use CentOS 6.6 for our application. I have profiled the application and find that we have a heavy requirement in terms of Disk writes. On an average when our application operates at a certain load i can observe that the disk writes / second is around 2 Mbps (Average). The block size set is 4k ******************* [root@localhost ~]# blockdev --getbsz /dev/sda3 4096 ******************* OS , Kernel Version: ***************** [root@localhost ~]# uname -a Linux localhost 2.6.32-504.el6.x86_64 #1 SMP Wed Oct 15 04:27:16 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux [root@localhost ~]# cat /etc/*release CentOS release 6.6 (Final) CentOS release 6.6 (Final) CentOS release 6.6 (Final) ***************** File-System being used: ******************** [root@localhost ~]# df -T Filesystem Type 1K-blocks Used Available Use% Mounted on /dev/sda3 ext3 100934056 20298152 75508688 22% / /dev/sda1 ext3 198337 34459 153638 19% /boot tmpfs tmpfs 16440152 0 16440152 0% /dev/shm ********************* I have a few queries with respect to the block size being set in the system: 1. Is 4k the optimum block size considering the amount of writes / second the application performs ? 2. How do i find out the optimum block size given the application load in terms of reads / writes per second ? 3. If there is a better block size that i can use , Can you suggest one ? 4. What are the pros / Cons of changing the default block size ? 5. We use ext3 as the file system for the partition which has heavy writes per second , Should we migrate it to ext4 ? Any pros / cons for it ? Appreciate any response / pointers in this regard. Thanks Jatin

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Firewalld broken on Centos7?
by Andrew Holway 19 Aug '15

19 Aug '15

Hi, I have a standard Centos7 AMI. Can anyone tell me whats happening here? Thanks, Andrew Aug 19 11:17:23 master dhclient[22897]: bound to 10.141.10.49 -- renewal in 1795 seconds. Aug 19 11:17:24 master network: Determining IP information for eth0... done. Aug 19 11:17:24 master network: [ OK ] Aug 19 11:17:24 master systemd: Started LSB: Bring up/down networking. Aug 19 11:23:43 master firewalld: 2015-08-19 11:23:43 ERROR: Failed to apply rules. A firewall reload might solve the issue if the firewall has been modified using ip*tables or ebtables. Aug 19 11:23:43 master firewalld: 2015-08-19 11:23:43 ERROR: '/sbin/iptables -D INPUT_ZONES -t filter -i eth0 -g IN_public' failed: iptables: No chain/target/match by that name. Aug 19 11:23:43 master firewalld: 2015-08-19 11:23:43 ERROR: COMMAND_FAILED: '/sbin/iptables -D INPUT_ZONES -t filter -i eth0 -g IN_public' failed: iptables: No chain/target/match by that name. Aug 19 11:35:58 master yum[23685]: Erased: cloud-init-0.7.5-10.el7.centos.1.x86_64

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shared memory - shmmax - shmall - page_size
by Michael H 19 Aug '15

19 Aug '15

Hi List, I'm tuning up a new database server and I'm finding very mixed information online. Here are the default shmmax and shmall from my new system cat /proc/sys/kernel/shmmax 4294967295 cat /proc/sys/kernel/shmall 268435456 SHMALL is close enough to being SHMMAX / 16. Now, everything I'm finding online tells me that SHMALL = SHMMAX / PAGE_SIZE. default page size is 4096. Has something changed in this calculation? should the defaults be set on SHMALL = SHMMAX / 16?? I'm running CentOS Linux release 7.1.1503 (Core), my old database is running CentOS release 6.6 (Final) and I'm seeing the same calculations there too. Can somebody please point me in the right direction, I've had a look at pgtune here http://pgtune.leopard.in.ua/, I will not be using the 'default' calculated configuration that it suggests but I noticed the shmall = shmmax / page_size (4096). I'll benchmark with both calculations but I would really appreciate some confirmation on this. thanks Michael

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[OT] C7 and php mkdir
by Alessandro Baggi 19 Aug '15

19 Aug '15

Hi list, I've a problem using PHP mkdir() with apache on C7. I'm trying to create a directory under a specified directory in the tree of my vhost, and mkdir create this directory but when I try to create a file in this dir I get error on permission. For directory creation I use permission 0777 for max perms to ensure that it works but I get invalid perm: dr----x--t. 2 apache apache ... I've tried also using: $old = umask(0); mkdir.... umask($old); with result: dr------wT. 2 apache apache ... Tried also chmod with umask(), same result. Selinux is disabled. Can someone point me in the right direction?. Thanks in advance.

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CentOS-announce Digest, Vol 126, Issue 9
by centos-announce-request＠centos.org 19 Aug '15

19 Aug '15

Send CentOS-announce mailing list submissions to centos-announce(a)centos.org To subscribe or unsubscribe via the World Wide Web, visit http://lists.centos.org/mailman/listinfo/centos-announce or, via email, send a message with subject or body 'help' to centos-announce-request(a)centos.org You can reach the person managing the list at centos-announce-owner(a)centos.org When replying, please edit your Subject line so it is more specific than "Re: Contents of CentOS-announce digest..." Today's Topics: 1. CESA-2015:1640 Moderate CentOS 6 pam Security Update (Johnny Hughes) 2. CESA-2015:1640 Moderate CentOS 7 pam Security Update (Johnny Hughes) ---------------------------------------------------------------------- Message: 1 Date: Tue, 18 Aug 2015 15:30:42 +0000 From: Johnny Hughes <johnny(a)centos.org> To: centos-announce(a)centos.org Subject: [CentOS-announce] CESA-2015:1640 Moderate CentOS 6 pam Security Update Message-ID: <20150818153042.GA2569(a)n04.lon1.karan.org> Content-Type: text/plain; charset=us-ascii CentOS Errata and Security Advisory 2015:1640 Moderate Upstream details at : https://rhn.redhat.com/errata/RHSA-2015-1640.html The following updated files have been uploaded and are currently syncing to the mirrors: ( sha256sum Filename ) i386: 290b2de5b11274bedd3dc14b63bacfc1794b2c4208e4e29979c4c7428eb7964f pam-1.1.1-20.el6_7.1.i686.rpm 6da9c1315ae8d24e44544eed02e3a9fe0c7eece7648bc5b52a3b65a46a86fec8 pam-devel-1.1.1-20.el6_7.1.i686.rpm x86_64: 290b2de5b11274bedd3dc14b63bacfc1794b2c4208e4e29979c4c7428eb7964f pam-1.1.1-20.el6_7.1.i686.rpm 6c9678f3372acbb5f652c2daf83c1f6ecd80b31b79c2b1b61c333c34a179dcdd pam-1.1.1-20.el6_7.1.x86_64.rpm 6da9c1315ae8d24e44544eed02e3a9fe0c7eece7648bc5b52a3b65a46a86fec8 pam-devel-1.1.1-20.el6_7.1.i686.rpm a39aae7c68c958278ba676170b8b8b29429cd74618f2dd1b5a7a6886cfa29458 pam-devel-1.1.1-20.el6_7.1.x86_64.rpm Source: a47936b7aad2c540af234b821224a9ece34577f1f9e6e94974cc91112e850bde pam-1.1.1-20.el6_7.1.src.rpm -- Johnny Hughes CentOS Project { http://www.centos.org/ } irc: hughesjr, #centos(a)irc.freenode.net ------------------------------ Message: 2 Date: Tue, 18 Aug 2015 16:19:11 +0000 From: Johnny Hughes <johnny(a)centos.org> To: centos-announce(a)centos.org Subject: [CentOS-announce] CESA-2015:1640 Moderate CentOS 7 pam Security Update Message-ID: <20150818161911.GA8287(a)n04.lon1.karan.org> Content-Type: text/plain; charset=us-ascii CentOS Errata and Security Advisory 2015:1640 Moderate Upstream details at : https://rhn.redhat.com/errata/RHSA-2015-1640.html The following updated files have been uploaded and are currently syncing to the mirrors: ( sha256sum Filename ) x86_64: e0d36e10c6878fa9f1b0b7e9dc15deb22d795925856826ecc8619fd322f23892 pam-1.1.8-12.el7_1.1.i686.rpm 95e6dfc467787bfe47414daa88e9ce701ead0b791e399f891f8cedbce99ff979 pam-1.1.8-12.el7_1.1.x86_64.rpm d45322823151e2f613dcbe6fb4f30a4c3136c5416a68aeb640c8e3d014c3f1d4 pam-devel-1.1.8-12.el7_1.1.i686.rpm 59ee244c96662c9b7a9a739d88f6a33b8821c3def4ee425cb4d9f98181685508 pam-devel-1.1.8-12.el7_1.1.x86_64.rpm Source: a2f8e35f3ab15ebd7821384966adee39e4efaa3cc1fdd0a26b80efdb92301e81 pam-1.1.8-12.el7_1.1.src.rpm -- Johnny Hughes CentOS Project { http://www.centos.org/ } irc: hughesjr, #centos(a)irc.freenode.net ------------------------------ _______________________________________________ CentOS-announce mailing list CentOS-announce(a)centos.org http://lists.centos.org/mailman/listinfo/centos-announce End of CentOS-announce Digest, Vol 126, Issue 9 ***********************************************

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Converting HVM to PV kernel CentOS7
by Venkateswara Rao Dokku 19 Aug '15

19 Aug '15

Hi, I have installed CentOS 7 HVM kernel. I would like to convert it to CentOs 7 PV kernel. When googled about it, I found that this can be done by following commands yum install xen or yum install kernel-xen But, when I tried the below commands, I am getting the error *"No package kernel-xen available.**"* What am I missing here. Any help is much appreciated. -- Thanks & Regards, Venkateswara Rao Dokku.

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how do I stop automount of Hitichi Lifestudio USB drive
by Michael Hennebry 19 Aug '15

19 Aug '15

Most of the time, if I plug a USB drive into my computer, gnome/centos/whatever will ask me what I want to do with it. With a Hitachi Lifestudio, all the partitions mount without asking me. How do I stop that behavior? My suspicion is that the same kind of mechanism is what makes candy drops work. So far as I know, my backup drive is not candy, but I would still like to be able to control my computer. -- Michael hennebry(a)web.cs.ndsu.NoDak.edu "SCSI is NOT magic. There are *fundamental technical reasons* why it is necessary to sacrifice a young goat to your SCSI chain now and then." -- John Woods

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initial setup of centos linux 7 core license information license not accepted
by Dave Burns 18 Aug '15

18 Aug '15

Did all this happen because I switched monitors? Or because I did all my setup over ssh? Otherwise, this is an FYI for other newbies who get confused by this like I did. Yesterday I set up a new centos 7 install, did updates, made all the config tweaks I like to make, and rebooted at the end to see if it would start up properly. No problem. (I logged in as the single user to see if it worked but did *nothing* as that user and did the rest of my work over the network via ssh.) This morning I shut it down and moved to a different location with a *different monitor.* During boot, it stopped with the following on the screen: After [ OK ] Started D-Bus System Message Bus. ==================================================== ==================================================== Initial setup of CentOS 7 (Core) 1) [!] License information (License not accepted) Please make your choice from above ['q' to quit | 'c' to continue | 'r' to refresh]: My caffeine-deprived response was to try q, c, and r, none of which got me unstuck. Forced to actually use my brain, I typed 1. More confusing text appeared, and I finally understood that in order to accept the license I must type 2. Then I had to type 1 again for some reason. Then my machine booted. It is probably apparent that I wouldn't have all this text to email you if the process had been as smooth as described. I have elided a certain amount of cursing and hair-pulling as unnecessary and embarrassing detail. I am curious as to the cause of the timing of this interruption. An attempt at a helpful suggestion: I am assuming that in some other circumstance, I might have more than one problem presented to me to deal with at the same time using this interface. I should think that the prompt should read like this: Please choose the number of the item above that you wish to try to fix, 'q' to quit and shut down, 'c' to continue booting, or 'r' if you are unable to read this text (or wish to petition the gods for mercy). cheers, Dave

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C5 recent openssl update breaks mysql SSL connection
by tony＠softins.co.uk 18 Aug '15

18 Aug '15

I recently applied updates to a CentOS 5 box running MySQL. I've discovered that the new version of openssl, 0.9.8e-36.0.1.el5_11, breaks MySQL SSL connections. If I rename /lib/libssl.so.0.9.8e and replace it with the old version of that file from openssl-0.9.8e-27.el5_10.1 (not sure if that is the next oldest, but it was handy), then SSL connection to MySQL works again. I then performed cross-checks using the server with new libssl and the client with old, and then vice versa. What I found was that it didn't matter whether the server was started with the old libssl or the new libssl. In both cases, the mysql client would only connect using the old libssl, and not when using the new libssl. When it works with the old libssl, I can confirm that SSL is in use: mysql> \s -------------- mysql Ver 14.12 Distrib 5.0.95, for redhat-linux-gnu (i386) using readline 5.1 Connection id: 2 Current database: Current user: root@localhost SSL: Cipher in use is DHE-RSA-AES256-SHA The error with the new libssl looks like this: [root@hostname ~]# mysql ERROR 2026 (HY000): SSL connection error Has anyone else come across this? Is it a bug in SSL? Or a new restriction? Do I need to regenerate my certificates using the new openssl? Cheers Tony -- Tony Mountifield Work: tony(a)softins.co.uk - http://www.softins.co.uk Play: tony(a)mountifield.org - http://tony.mountifield.org

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