I’m using below command to transfer files cross server

scp -rc blowfish /source/directory/* username@domain.net:/destination/directory

Is there a way to transfer only files modified files just like update command for cp?

rsync is your friend.

rsync -ru /source/directory/* username@domain.net:/destination/directory

If you want it to delete files at the destination that no longer exist at the source, add the --delete option.

Check more discussion of this question.

Recent versions of RHEL/CentOS (EL6) brought some interesting changes to the XFS filesystem I’ve depended on heavily for over a decade. I spent part of last summer chasing down an XFS sparse file situation resulting from a poorly-documented kernel backport. Others have had unfortunate performance issues or inconsistent behavior since moving to EL6.

XFS was my default filesystem for data and growth-partitions, as it offered stability, scalability and a good performance boost over the default ext3 filesystems.

There’s an issue with XFS on EL6 systems that surfaced in November 2012. I noticed that my servers were showing abnormaly-high system loads, even when idle. In one case, an unloaded system would show a constant load average of 3+. In others, there was a 1+ bump in load. The number of mounted XFS filesystems seemed to influence the severity of the load increase.

System has two active XFS filesystems. Load is +2 following upgrade to the affected kernel.

Digging deeper, I found a few threads on the XFS mailing list that pointed to an increased frequency of the xfsaild process sitting in the STAT D state. The corresponding CentOS Bug Tracker and Red Hat Bugzilla entries outline the specifics of the issue and conclude that this is not a performance problem; only an error in the reporting of system load in kernels newer than 2.6.32-279.14.1.el6.

WTF?!?

In a one-off situation, I understand that the load reporting may not be a big deal. Try managing that with your NMS and hundreds or thousands of servers! This was identified in November 2012 at kernel 2.6.32-279.14.1.el6 under EL6.3. Kernels 2.6.32-279.19.1.el6 and 2.6.32-279.22.1.el6 were released in subsequent months (December 2012 and February 2013) with no change to this behavior. There’s even been a new minor release of the operating system since this issue was identified. EL6.4 was released and is now on kernel 2.6.32-358.2.1.el6, which exhibits the same behavior.

I’ve had a new system build queue and have had to work around the issue, either locking kernel versions at the pre-November 2012 release for EL6.3 or just not using XFS, opting for ext4 or ZFS, at a severe performance penalty for the specific custom application running atop. The application in question relies heavily on some of the XFS filesystem attributes to account for deficiencies in the application design.

Going behind Red Hat’s paywalled knowledgebase site, an entry appears stating:

High load average is observed after installing kernel
2.6.32-279.14.1.el6. The high load average is caused by xfsaild going into D state for each XFS formatted device.

There is currently no resolution for this issue. It is currently being
tracked via Bugzilla #883905. Workaround Downgrade the installed
kernel package to a version lower then 2.6.32-279.14.1.

(except downgrading kernels not an option on RHEL 6.4…)

So we’re 4+ months into this problem with no real fix planned for the EL6.3 or EL6.4 OS releases. There’s a proposed fix for EL6.5 and a kernel source patch available… But my question is:

At what point does it make sense to depart from the OS-provided kernels and packages when the upstream maintainer has broken an important feature?

Red Hat introduced this bug. They should incorporate a fix into an errata kernel. One of the advantages of using enterprise operating systems is that they provide a consistent and predictable platform target. This bug disrupted systems already in production during a patch cycle and reduced confidence in deploying new systems. While I could apply one of the proposed patches to the source code, how scalable is that? It would require some vigilance to keep updated as the OS changes.

What’s the right move here?

• We know this could possibly be fixed, but not when.
• Supporting your own kernel in a Red Hat ecosystem has its own set of caveats.
• What’s the impact on support eligibility?
• Should I just overlay a working EL6.3 kernel on top of newly-build EL6.4 servers to gain the proper XFS functionality?
• Should I just wait until this is officially fixed?
• What does this say about the lack of control we have over enterprise Linux release cycles?
• Was relying on an XFS filesystem for so long a planning/design mistake?

Edit:

This patch was incorporated into the most recent CentOSPlus kernel release (kernel-2.6.32-358.2.1.el6.centos.plus). I’m testing this on my CentOS systems, but this doesn’t help much for the Red Hat-based servers.

At what point does it make sense to depart from the OS-provided kernels and packages when the upstream maintainer has broken an important feature?

“At the point where the vendor’s kernel or packages are so horribly broken that they impact your business” is my general answer (coincidentally this is also about the point where I say it makes sense to start looking at ways to depart from the vendor relationship).

Basically as you and others have said, RedHat seems to not want to patch this in their distributed kernel (for whatever reason). That pretty much leaves you in the situation of having to roll your own kernel (keeping it up to date on patches yourself, maintaining your own package and installing it on your systems with Puppet or similar, or running a package server that Yum or whatever they use today can reference), or taking your marbles and going home.

Yes I know taking your marbles and going home is often an expensive proposition — switching OS vendors is a huge pain, especially in the Linux world where the flavors are radically different from an administrative standpoint.
Other options like going totally CentOS are also unappealing (because you lose support, and you’re still getting essentially RedHat’s code built by someone else so you’d still have this bug).

Unfortunately unless enough people (i.e. “huge companies) take their marbles and go home the vendor won’t care so much about screwing people over by shipping bad code and not fixing it.

Check more discussion of this question.

if i use any yum command, i get

Loaded plugins: fastestmirror
Traceback (most recent call last):
  File "/usr/bin/yum", line 29, in <module>
    yummain.user_main(sys.argv[1:], exit_code=True)
  File "/usr/share/yum-cli/yummain.py", line 285, in user_main
    errcode = main(args)
  File "/usr/share/yum-cli/yummain.py", line 114, in main
    base.doLock()
  File "/usr/lib/python2.6/site-packages/yum/__init__.py", line 1791, in doLock
    while not self._lock(lockfile, mypid, 0644):
  File "/usr/lib/python2.6/site-packages/yum/__init__.py", line 1861, in _lock
    os.write(fd, contents)
OSError: [Errno 28] No space left on device

If i use the top command i see this. If i use the df -h i see this.

Is it yum error? python error? or what?

EDIT

the output of find / -size +1G is

/var/log/squid/access.log-20130317
find: File system loop detected; `/var/named/chroot/var/named’ is part of the same file system loop as /var/named’.

find: /proc/31495/task/31495/fd/5': No such file or
directory find:/proc/31495/task/31495/fdinfo/5′: No such file or
directory find: `/proc/31495/fd/5′: No such file or directory find:

/proc/31495/fdinfo/5′: No such file or directory

Looks like / is full

While you have almost 500GB in /home.

You might wanna reallocate some more space to / for system use.

Also, check /var/log as it resides on /

It is very possible you have some huge log files that could be pruned to clear up some space. 10G isnt much, but can be enough.

Check more discussion of this question.

Been trying to run

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o venet0:0 -j MASQUERADE

and I keep getting the above error message. Trying to set up openvpn on my server.

Does anyone have any idea how to solve this?

firstly, venet0:0 is not valid, just use venet0, iptables does not care about interface labels.

The error itself is down to the fact that either you do not have the nat table kernel module loaded or you do, but don’t have MASQUERADE.

Since this is OpenVZ, you would need to ask your host to provide it.

Check more discussion of this question.

I have installed centos 5.8 with Hetzner server rescue mode but its disk parttion table is in MSDOS formate which does not support more than 2 TB space of disk so i need to change the partition table into GPT formate.but enable to install os in Gpt formate how can i cange parttion table formate from dos to gpt.
Thanks in advance.

You don’t. GPT support is available on EL6, but not on EL5.

So Hetzner should never have offered you this distribution.

To resolve the issue, install CentOS 6 instead.

Check more discussion of this question.

I extracted the httpd…tar.gz from here, but I don’t see apachectl.

[vagrant@centos48 opt]$ ls
httpd-2.2.23  httpd-2.2.23.tar.gz
[vagrant@centos48 httpd-2.2.23]$ find . -name apachectl
[vagrant@centos48 httpd-2.2.23]$ 

This is because you did not build the code. You downloaded the source code. So, you need to build it first to create the binaries and libraries.

Check more discussion of this question.

When running the following command, yum hangs on Setting up repositories.

[vagrant@centos48 yum.repos.d]$ sudo yum install emacs
Setting up Install Process
Setting up repositories

yum.conf

[vagrant@centos48 ~]$ cat /etc/yum.conf 
[main]
cachedir=/var/cache/yum
debuglevel=2
logfile=/var/log/yum.log
pkgpolicy=newest
installonlypkgs=kernel kernel-smp kernel-devel kernel-smp-devel kernel-largesmp kernel-largesmp-devel kernel-hugemem kernel-hugemem-devel
distroverpkg=centos-release
tolerant=1
exactarch=1
retries=20
obsoletes=1
gpgcheck=1
plugins=1proxy= [intentionally not listed]# PUT YOUR REPOS HERE OR IN separate files named file.repo
# in /etc/yum.repos.d

CentOS-Base.repo

Note that I got the same error as before when commenting out [base]‘s baseurl, but leaving mirrorlist uncommented.

# CentOS-Base.repo
#
# This file uses a new mirrorlist system developed by Lance Davis for CentOS.
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the
# remarked out baseurl= line instead.
#
#[base]
name=CentOS-$releasever - Base
#mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
baseurl=http://mirror.centos.org/centos/$releasever/os/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
priority=1
protect=1#released updates
[update]
name=CentOS-$releasever - Updates
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
#baseurl=http://mirror.centos.org/centos/$releasever/updates/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
priority=1
protect=1#packages used/produced in the build but not released
[addons]
name=CentOS-$releasever - Addons
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons
#baseurl=http://mirror.centos.org/centos/$releasever/addons/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
priority=1
protect=1#additional packages that may be useful
[extras]
name=CentOS-$releasever - Extras
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
#baseurl=http://mirror.centos.org/centos/$releasever/extras/$basearch/
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
priority=1
protect=1#additional packages that extend functionality of existing packages
[centosplus]
name=CentOS-$releasever - Plus
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
#baseurl=http://mirror.centos.org/centos/$releasever/centosplus/$basearch/
gpgcheck=1
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4
priority=2
protect=1

This is because your server is running an old version of CentOS 4, which went End-of-Life in February 2012. The files have been moved to the CentOS Vault. Your repo files would need to be modified in order to continue to use this OS with the YUM framework.

You can update your /etc/yum.repos.d/CentOS-Base.repo file to point to the new location as so:

# CentOS-Base.repo
#
# This file uses a new mirrorlist system developed by Lance Davis for CentOS.
# The mirror system uses the connecting IP address of the client and the
# update status of each mirror to pick mirrors that are updated to and
# geographically close to the client.  You should use this for CentOS updates
# unless you are manually picking other mirrors.
#
# If the mirrorlist= does not work for you, as a fall back you can try the 
# remarked out baseurl= line instead.
#
#[base]
name=CentOS-$releasever - Base
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
baseurl=http://vault.centos.org/4.9/os/$basearch
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4#released updates 
[update]
name=CentOS-$releasever - Updates
mirrorlist=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
baseurl=http://vault.centos.org/4.9/updates/$basearch
gpgcheck=1
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos4

Check more discussion of this question.

I’ve been experiencing this problem with oidentd for a couple of days and I can’t seem to be able to find a solution to this yet.
oidentd seems to give me headaches every time I want to get it work on different servers.

I have to mention I’ve installed oidentd using rpm package (oidentd-2.0.8-8.el6.i686 more exactly) because directly typing yum install oidentd didn’t work for some unknown reason.
I want to use it in order to make ZNC on the server reply to ident requests with each username’s ident.

After finally installing it, I’ve done the configs and stuff (exactly the same configs I’ve done to the other server which seem to work fine):

$ nano /etc/oidentd.conf to this:

default {
        default {
            allow spoof
            deny spoof_all
            deny spoof_privport
            allow random_numeric
            allow numeric
            allow hide
        }
}user root {
        default {
            force reply "UNKNOWN"
        }
}

Installed ZNC 1.0 using the source tarball.
I made a user called znc and then run ZNC from it.
Then I went to my client and enabled the identfile module. Set the spoof file for the per user configuration to ~/.oidentd.conf and the format to global { reply "%ident%" }.
Made sure the user has chmod access to ~/.oidentd.conf file. All perfect, like how it was configured on the other server.

Everything went great, no errors, *identfile even told me what would the format be expanded to, I was happy and excited to see nothing was going wrong.

Until I reconnected to the server.
It gives an ident response (sign that oidentd is working?) but the problem is that it always replies with the username I’m running ZNC with (which would be znc)

Here’s a small output to make everything clear:

[msg: *identfile]: getfile
(*identfile) File is set to: ~/.oidentd.conf
[msg: *identfile]: getformat
(*identfile) Format is set to: global { reply "%ident%" }
(*identfile) Format would be expanded to: global { reply "Tarmac" }Please wait while we process your connection.
*** Checking Ident
*** Got Ident response

Then I did a WHOIS on my nick:

WHOIS Tarmac
[whois: Tarmac] (registered nick)
name: bri
address: znc@random.geek

I tried restarting oidentd and ZNC n times, but no result. Still the same replies.

I don’t really know what’s wrong here, but looks like there’s either a problem with ZNC or a problem with oidentd. The only suspicion I’ve got so far is that probably oidentd is not working as it should or *identfile module is not properly writing the format to the spoof file.

I’m so confused right now, so any suggestion on solving this would be highly appreciated.
Thank you!

Edit: another heads-up, it seems that they removed oidentd from the packages? I don’t know why though… if I install rpm does the linux kernel matter that much? I’ve been trying different rpm’s but none seems to give any result…

Edit2: I’ve tried installing oidentd from the source. Install went OK, with no issues.

I tried disabling *identfile while I thought it was the issue, edited /home/znc/.oidentd.conf to global reply { "testident" } but it still replies with znc unless I add this to the /etc/oidentd.conf :

user "znc" {
    default {
        force reply "testident"
    }
}

So basically I made an edit in /etc/oidentd.conf to force reply with a specific ident for the user znc…
It seems to work, but when I go to the per-user config and try the same thing, then it doesn’t. I don’t even… !

It seems that there’s a problem with reading the per user configuration… but not sure what? I set the chmodes and stuff to the correct settings yet it doesn’t work as it should.

Thanks again.

It looks like I had to delete /home/znc/.oidentd.conf and let it make a new one alone…
I don’t even know how this solved the problem because I tried the same thing earlier and I let it make the ~/.oidentd.conf by itself after installing ZNC, but… I’m glad it finally works now haha!

Check more discussion of this question.

I have a CentOS server with a plesk control panel installed, I used to login using SFTP with the root password to manage the files. However, and all of a sudden, I am not able to access the server using SFTP and I get this error when using CuteFTP

ERROR:>     [4/18/2012 5:18:31 PM] Connection to the server was lost, and the operation could not be performed.
ERROR:>     [4/18/2012 5:18:31 PM] Can't connect to localkicks.com:22. SFTP21 error = #7. 0

I tried restarrting sshd on linux but with no luck, how do I troubleshoot this?

Appreciate the help.

Yehia A.Salam

I tried WinSCP and it works now, however i’m not sure why in the first place the sftp was not working

Check more discussion of this question.

I’ve just puppetted a virtual machine and from scratch (based on Centos 6.3 minimal). That install process does a variety of things, but one annoying side effect is that when the VM reboots, it automatically opens a tool called:

Text Mode Setup Utility 1.19.9    (c) 1999-200 Red Hat, Inc.

Is says “Choose a Tool” with options for “Authentication configuration”, “Firewall configuration”, “Keyboard configuration”, “Network configuration”. I don’t think it serves a purpose as the VM is sufficiently well configured for what we need to use it for, but it’s annoying that it doesn’t restart to the normal login prompt.

Can anyone tell me how to stop this Text Mode Setup Utility running? Is it a missing configuration option or a spurious package I’ve installed?

— Update 1 —

Here’s the output of chkconfig. It looks like firstboot is running. I didn’t know what that is, but now I’ve read:

http://www.centos.org/docs/5/html/5.1/Deployment_Guide/s2-sysconfig-firewall.html

so I’ll touch /etc/sysconfig/firstboot, which should stop it happening?

NetworkManager  0:off   1:off   2:on    3:on    4:on    5:on    6:off
auditd          0:off   1:off   2:on    3:on    4:on    5:on    6:off
avahi-daemon    0:off   1:off   2:off   3:on    4:on    5:on    6:off
cgconfig        0:off   1:off   2:off   3:off   4:off   5:off   6:off
cgred           0:off   1:off   2:off   3:off   4:off   5:off   6:off
crond           0:off   1:off   2:on    3:on    4:on    5:on    6:off
csf             0:off   1:off   2:on    3:on    4:on    5:on    6:off
dnsmasq         0:off   1:off   2:off   3:off   4:off   5:off   6:off
firstboot       0:off   1:off   2:off   3:on    4:off   5:on    6:off
haldaemon       0:off   1:off   2:off   3:on    4:on    5:on    6:off
httpd           0:off   1:off   2:off   3:off   4:off   5:off   6:off
ip6tables       0:off   1:off   2:on    3:on    4:on    5:on    6:off
iptables        0:off   1:off   2:on    3:on    4:on    5:on    6:off
lfd             0:off   1:off   2:on    3:on    4:on    5:on    6:off
lvm2-monitor    0:off   1:on    2:on    3:on    4:on    5:on    6:off
mdmonitor       0:off   1:off   2:on    3:on    4:on    5:on    6:off
memcached       0:off   1:off   2:on    3:on    4:on    5:on    6:off
messagebus      0:off   1:off   2:on    3:on    4:on    5:on    6:off
mysqld          0:off   1:off   2:on    3:on    4:on    5:on    6:off
netconsole      0:off   1:off   2:off   3:off   4:off   5:off   6:off
netfs           0:off   1:off   2:off   3:on    4:on    5:on    6:off
network         0:off   1:off   2:on    3:on    4:on    5:on    6:off
ntpd            0:off   1:off   2:on    3:on    4:on    5:on    6:off
ntpdate         0:off   1:off   2:off   3:off   4:off   5:off   6:off
postfix         0:off   1:off   2:on    3:on    4:on    5:on    6:off
puppet          0:off   1:off   2:off   3:off   4:off   5:off   6:off
rdisc           0:off   1:off   2:off   3:off   4:off   5:off   6:off
restorecond     0:off   1:off   2:off   3:off   4:off   5:off   6:off
rsyslog         0:off   1:off   2:on    3:on    4:on    5:on    6:off
saslauthd       0:off   1:off   2:off   3:off   4:off   5:off   6:off
spice-vdagentd  0:off   1:off   2:off   3:off   4:off   5:on    6:off
sshd            0:off   1:off   2:on    3:on    4:on    5:on    6:off
svnserve        0:off   1:off   2:off   3:off   4:off   5:off   6:off
udev-post       0:off   1:on    2:on    3:on    4:on    5:on    6:off
wdaemon         0:off   1:off   2:off   3:off   4:off   5:off   6:off
wpa_supplicant  0:off   1:off   2:off   3:off   4:off   5:off   6:off
zend-server     0:off   1:off   2:on    3:on    4:on    5:on    6:off

— Update 2 —-

Alas no. I also tried editing to /etc/sysconfig/firstboot to include the line RUN_FIRSTBOOT = no, as described at http://forum.eltechsupport.com/operating-system/run-firstboot-on-linux/ but another reboot and the tool is still popping up. Can you tell me how to disable it? Also, might you cast an expert eye down the list of services running and tell me if there’s anything else I shouldn’t be running on a production webserver please?

— Update 3 —

Thanks. That worked a treat. Marking as answer:

sudo chkconfig firstboot off

Can you show the output of chkconfig? How about your kickstart file? Is firstboot enabled?

Make sure you haven’t activated the sys-unconfig functionality. This places a file in /.unconfigured which can start the setup tool you’re referring to.

The name of the package that the utility belongs to is setuptool.

Check more discussion of this question.