howto yum upgrade fedora 14 to fedora 15

<edited 29May2011>

so fedora 15 is out. and we want to upgrade to the latest and greatest. i decided to follow this but i came across some problems.

just a hint that when you upgrade you may need to babysit in through as gnome stuff might stop the upgrade

systemd resources

tomorrow the 23rd of May 2011, fedora 15 will be made available to the general public. the biggest change for me is the replacement of sysv init system and/or upstart with systemd.i am going to put the basic of systemd here however at the end of this article is a list of resources for further reading which i urge to do so.

howto lock the cdrom

any geek with kids is going to understand when there are times the geek wants to keep the cdrom in the drive and not popping in and out and in and out and ...so how to lock the cdrom or dvdrom drive in? well this link tells you to use eject but to spare you the time and to replicate the knowledge on the net, it is:

sshfs

sshfs is a fuse filesystem. using the same idea as nfs, it allows you to mount remote filesystems over ssh.

to mount the directory

sshfs user@remote.host:/remote/dir /local/mount/dir

and to unmount the directory

fusermount -u /local/mount/dir

and thats it

howto mirror a volume group

mirroring is a raid technique where all data on the first disk is mirrored identically on the file on a second disk. the advantage of any raid technique is visible when a disk goes bad, but your data is still safe and you have the opportunity to replace the bad disk.
in our example we are going to mirror rootvg. note that rootvg has some additional steps to use the 2nd disk in a disaster situation. on AIX unless you are doing some sort of custom configuration rootvg is on hdisk0

1. extend the rootvg to the second disk

howto extend lv in aix

Extending a filesystem on AIX is similar to linux. you add the physical disk to the system. you convert the physical disk to a physical volume (pv) then you add the pv to the volume group (vg) then you extend the logical volume (lv) with the newly assigned space. then you extend the filesystem on the lv.

in the following example we want to add 1Gb to /home/user1. where /home/user1 is an lv by itself. the most common use is normally /oracle in the enterprise (or /u01 or wherever you installed oracle) or /home on the home desktop.

and here are the commands:

howto extend the logical volume in linux

Recently, I added a new hard disk to my linux box and I decided to document it the process of how to extend to root partition over the 2 disks.

First of all the disk was the 2nd disk on the system so it was /dev/sdb

so we do a

pvcreate /dev/sdb

then we add this new pv we created to an already existing lv. for the purposes of this document let us call it lv_root

oracle.repo

sometime back, i was building an oracle rac with oracle linux 5.x when i discovered on the same dvd an rpm by the name of oracle-validated. this link is the first introduction of the world to the rpm.

howto fix 0315-180 logread: UNEXPECTED EOF on errpt log

so i was trying to view the error report for an aix machine but i got some unexpected output.

# errpt -a
0315-180 logread: UNEXPECTED EOF
0315-171 Unable to process the error log file /var/adm/ras/errlog.
0315-132 The supplied error log is not valid: /var/adm/ras/errlog.


the steps below are what i did to fix it courtesy of ITToolBOX

switching user

following the very essential (and blasphemous) concept "root is god". any decent system administrator will never ever log in as root directly. instead the SA should log in as his normal user account and then switch user to run the command as root

switching user can be done in 2 ways:

su -c <command>
sudo <command>

the question arises: what's the difference?

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