Discuss June 2011

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206 participants
141 discussions

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

7 9

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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Re: [CentOS] Dell openmanage srvadmin on 5.6
by Roy Trubshaw 15 Jun '11

15 Jun '11

Kevin wrote: > I'm just trying to get Dell openmanage to run on my Centos 5.6 > box. The monitoring [ Snipped ] > > Can anyone point me at a suitable rpm, or do I have to resort to > compiling it? Surely I'm not > the only one trying to do this. > > -- > Kevin Thorpe This is my fault. I enabled the 'priority' plugin as a short-term fix because we have a lot of repositories and I wasn't entirely sure which ones could be discarded. The dell-omsa repo seems to have lost its priority=1 line and the plugin seems to assume priority=<bignumber> and thus the dell repo was being excluded. Added the priority=1 line and everything installed OK. (Yes I will tell him as he sits opposite me but the list deserved to know the answer too.) -- Roy

1 0

leaving ports open for tftp
by Tim Dunphy 14 Jun '11

14 Jun '11

hey guys, I have a really silly question for you! I just built a cobbler server that I am using to bare metal some boxes. But I am a bit n00b and need to figure out which ports to open in iptables. Here's a start: xinetd 2031 root 8u IPv4 94306 UDP *:tftp in.tftpd 9203 root cwd DIR 253,0 4096 588097 /tftpboot in.tftpd 9203 root rtd DIR 253,0 4096 2 / in.tftpd 9203 root txt REG 253,0 39544 1813945 /usr/sbin/in.tftpd in.tftpd 9203 root mem REG 253,0 139504 1698969 /lib64/ld-2.5.so in.tftpd 9203 root mem REG 253,0 1722304 1698999 /lib64/libc-2.5.so in.tftpd 9203 root mem REG 253,0 37368 1699127 /lib64/libwrap.so.0.7.6 in.tftpd 9203 root mem REG 253,0 114352 1699014 /lib64/libnsl-2.5.so in.tftpd 9203 root mem REG 253,0 53880 1698970 /lib64/libnss_files-2.5.so in.tftpd 9203 root 0u IPv4 94306 UDP *:tftp I think what I want is the 6th column but I am uncertain of how to express that in terms of iptables. Thanks! tim

2 1

OT: clear error from premature disk removal from LVM
by Keith Keller 14 Jun '11

14 Jun '11

Hi all, This question is only slightly ontopic, in that the host system is a CentOS 5 box, but is otherwise a fairly generic question. I've looked in so many different places for an answer, but haven't had much luck, so I'm hoping someone here has some advice. (for the record: I posted this question to comp.os.linux.misc a few weeks ago) === I made a minor mistake recently, and am trying to determine the cleanest way to clear it. Attached to my hardware RAID controller were two RAID6 units. One was the original disks that came with the server, which originally hosted our data, but had since had all its data migrated to a new LVM PV. The other is newer disks with a new PV, VG, and LV. For testing purposes, after completing the pvmove I created a clean, new LV on the unit containing the old disks. (I believe that I actually destroyed the original RAID6 array and created a new one.) Unfortunately, I completely forgot about this LV during a recent hardware upgrade, and didn't run through the LVM steps to completely remove an unused physical volume before removing these old disks. (At least the LV was not mounted at the time). Now LVM seems to be confused about the disks and volumes that are available, and the kernel may also be confused. Taken from a recent reboot, here's the dmesg log entry for the old testing unit: sd 1:0:2:0: Attached scsi disk sdc Later on, I removed the disks through the controller's tools, replaced them with new ones (so this is the third set of disks), and created a new RAID6 unit. After making the new unit I see (among other messages which don't seem helpful): May 19 16:27:28 xxxx kernel: sd 1:0:2:0: Attached scsi disk sdd Later on, when trying to run parted or friends, I see messages like so: May 23 11:22:47 xxxx kernel: scsi 1:0:2:0: rejecting I/O to dead device (note the same scsi address as sdc?) And pvdisplay says: # pvdisplay /dev/testVG/testLV: read failed after 0 of 4096 at 0: Input/output error That looks bad--it seems like testLV is trying to find the old LVM on /dev/sdc, but the array on sdd is there instead. Worse, I fear that trying to manipulate sdd may cause problems in the future, so am wary of doing anything with it before I clear up this issue. What should my next steps be? I've seen recommendations (in other somewhat similar situations) to try an lvscan or vgscan to refresh the list of volumes; or to try vgreduce --removemissing to remove the now-gone volumes from what LVM thinks is there. I do also still have the original disks, which I could put back and try to get LVM to re-find, but would be a pain. I am hoping to avoid a reboot, since the current LV seems unaffected and is in use, but I can do it if it's the surest way to make sure my LVM configuration is clean. I should point out that I do not care at all about the data on testLV; all I want to do is cleanly tell LVM not to worry about that volume any more, and be in a position to use the third set of disks safely and reliably. Thanks for reading--I hope you can help. --keith -- kkeller(a)wombat.san-francisco.ca.us

1 0

Compiling PHP and MySQL
by Dvorkin, Asya 14 Jun '11

14 Jun '11

Hi everyone, I need to install an older version of PHP - 5.2.16, which is not currently available through an official CentOS repo (as far as I can tell). In order to fulfill our developer's requirements, I've decided to just compile PHP and MySql from the source. Is there a way to find out what are the usual configure options that are used to compile binaries that are available through yum? Thank you! Asya

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Dell openmanage srvadmin on 5.6
by Kevin Thorpe 14 Jun '11

14 Jun '11

Hi all, I'm just trying to get Dell openmanage to run on my Centos 5.6 box. The monitoring stuff appears to have installed but the web server stuff is complaining it needs openwsman 2.2.3 or later and I can only find that for RHEL/Centos 6, not 5. Can anyone point me at a suitable rpm, or do I have to resort to compiling it? Surely I'm not the only one trying to do this. -- Kevin Thorpe

3 6

Bash rotating tab completion with list
by Dotan Cohen 14 Jun '11

14 Jun '11

I just got off a Windows 7 terminal which has rotating tab completion, this means that in the case of completion ambiguity the shell completes one of the possibilities, and subsequent tabs complete to different possibilities. This in contrast to bash's behaviour of simply printing a list of possibilities. Googling I have found that bash can in fact have rotating completion by setting "\C-i": menu-complete. However, I would really like the first tab to show the possibilities (default behaviour, albeit on the second tab), and subsequent tabs to rotate. I can't figure this out. Any ideas? Thanks! -- Dotan Cohen http://gibberish.co.il http://what-is-what.com

2 4

Recall: EXTERNAL: A bridge problem
by Massey, Ricky 14 Jun '11

14 Jun '11

Massey, Ricky would like to recall the message, "EXTERNAL: [CentOS] A bridge problem".

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Discuss June 2011