Posts Tagged linux

Howto: Restore VG with LVM backup.

Like cbr in VxVM, LVM has also backup in /etc/lvm/archive/, so if you accidentally remove VG, or VG got destroyed. you can try following procedure.

Note: better do disk2disk copy before doing following. No grantee for your data.

[root@mytesthost:~]# cd /etc/lvm/archive/

[root@mytesthost:/etc/lvm/archive]# ls -lart .
total 36
-rw——- 1 root root 919 Oct 22 13:34 VG-data_00000-1897227548.vg
-rw——- 1 root root 923 Oct 22 13:51 VG-data_00001-659586034.vg
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(Fixed) Oracle RAC Issue – cssd

Issue 1: cssd can’t start up during reboot. GC startup block cssd startup. disable GC auto start fixed the issue.

root@host_name# /ora/product/11.1.0.6a/bin/crsctl check crs
Failure 1 contacting Cluster Synchronization Services daemon
Cannot communicate with Cluster Ready Services
Cannot communicate with Event Manager

root@host_name# /ora/product/11.1.0.6a/bin/crsctl start crs
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ssh: access denied for user

Issue:
Jun 20 03:18:04 localhost sshd[512]: Failed password for iamid from 10.x.x.1 port 44241 ssh2
Jun 20 03:18:04 localhost sshd[513]: fatal: Access denied for user iamid by PAM account configuration

check /var/log/secure, got above messages.

tips to troubleshooting:

1. /etc/nologin exists or not, if exists, remove it.
2. /etc/security/access.conf, whether your group/user exists in allow list.

if still have issue, turn on DEBUG for sshd.

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Home permission

when we open user_dir in apache, we should change the /home as 711
i changed it to 711 no,but still have some problems

the developer use Ruby , it shows the following in apache error log.
Permission denied: xsendfile: cannot open file:
change the directory that store the file, it works well.

so seldom use /home/user to store some files that apache will visit.

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Use Google Js API or YUI if u can

at the title, benefits in short
1. the Google use CDN, so the clients can browser faster than your own server.
2. use it can save ur bandwidth and network usage
3. Increases Number Of Parallel Downloads

but in China, maybe not well enough, because the Google is f**ked sometimes.

Refer: Read the rest of this entry »

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Web Cookies

The programmers met a problem when use Typo3, the clients can’t login with IE but can login with Firefox/Opera.
After the investigation , we find the problem is the cookies. Typo3 can set the domain for the cookies. change the setting to “.domain.com” it works.

btw, close the browers and clean the cookies the most right way.
In order to do this properly, remember to close your browser first. This is because all your cookies are held in memory until you close your browser. So, if you delete the file with your browser open, it will make a new file when you close it, and your cookies will be back.

Refer of the cookies.
http://www.cookiecentral.com/faq/
http://www.howstuffworks.com/cookie.htm
http://tools.ietf.org/html/rfc2109
http://tools.ietf.org/html/rfc2965

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Troubleshooting UNIX Systems with Lsof(From Internet)

So excellent articles, but the blogspot.com is blocked by STH. so i paste it here.
Original Link: http://0xfe.blogspot.com/2006/03/troubleshooting-unix-systems-with-lsof.html

One of the least-talked-about tools in a UNIX sysadmin’s toolkit is lsof. Lsof lists information about files opened by processes. But that’s really an understatement.

Most people forget that, in UNIX, (almost) everything is a file. The OS makes hardware available to applications by way of files in /dev. Kernel, system, memory, device etc. information in made available inside files in /proc. TCP/UDP sockets are sometimes represented internally as files. Even directories are really just files containing other filenames.
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A good site for Linux geek

http://www.thegeekstuff.com/

there are lots of articles on Linux/Vim/Others.
they dig depth of the linux commands.

e.g.
lshw -class memory
lshw -class disk
lshw -short

class type:
address
bridge
bus
communication
disk
display
generic
input
memory
multimedia
network
power
printer
processor
storage
system
tape
volume

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Create Ur own Repo for CentOS or RPM base distro

1. create ur own packages, put it into www home directory. let clients can visit from network
such as /var/www/html/my_repo
http://my_ip/my_repo even ftp://my_ip/my_repo

2. create u repo files on clients
e.g.
cat /etc/yum.repos.d/ceph.repo
[ceph]
name=My Cluster Repo $basearch
baseurl=http://my_ip/my_repo
enabled=1
gpgcheck=0 # if u read further, we should change it to “1” for security.

3. yum search some_pkgs
u should get ur repo now.

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Rpm error when rpmbuild

I met the problem when i rebuild the ceph

Q: RPM build errors:
Installed (but unpackaged) file(s) found:

A: add the files to
ur_package_name.spec

%file
…..
…..
ur files that unpacked

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