They are all good. But that's not a real tip. What you should be looking for is which distribution you feel the most comfortable with. RedHat has the reputation of being very easy to install. They are lots of method on the different distribution to install the OS.
Tuesday, November 22, 2011
Tips: 1 Which distribution is good for you
Saturday, October 1, 2011
Veritas Volume Manager
Generic Tasks
Assumption: Veritas software has been installed and that rootdg has been setup by the installer with a minimum of one disk. If not, install the software now.
Use the "format" command to display available disks. If necessary, add new disks to the system and run "drvconfig; devlinks; disks" to configure the new disks. Do not partition disks to be used by Veritas.
To display disks setup for Veritas, use the command "vxdisk list".
To add more disks to the control of Veritas, use the following command:
The would be c2t0d0, for example, without the slice suffix. The vxdiskadd script will prompt for necessary information such as the name of the disk group, whether or not to initialize the new disk, etc. Rerun the command "vxdisk list" to view the new disk.
To designate an unused disk as a hot-spare disk, use the following command:
The would be the Veritas name for the disk, such as disk01. Use "vxdisk list" to confirm that the disk is now a dedicated hot-spare disk. To remove the disk from the dedicated hot-spare pool, use the following command:
By default, Veritas will name disks based on the name of the disk group. To rename a disk (for example, from disk01 to disk02), use the following command:
To place a disk offline (for example, if the disk has become corrupted), run the following command:
The would be c2t0d0, for example, without the slice suffix.
To remove a disk from the diskgroup to which it belongs, run the following command:
To then remove that disk from Veritas control entirely, run the following command:
The same set of commands may be used to move disks from one diskgroup to another:
Alternatively, you can simply remove the disk from Veritas control and then reinitialize it with "vxdiskadd". Use "vxdisk list" to confirm the new affiliation.
Every disk group requires a minimum of one disk. The simplest way to add a new diskgroup is to run the "vxdiskadd" command on an unconfigured disk, and when prompted for the name of the diskgroup to use, enter the desired name of the new diskgroup.
To display information on disk groups, run "vxdg list" or "vxdg list".
To destroy a diskgroup and reuse the disks for other purposes, run the following command:
Failing or failed disks can be removed with the "vxdiskadm" menu command. To remove a failing disk, select choice 4, "remove a disk for replacement". To replace the disk later, select choice 5, "replace a failed or removed disk".
The Volumes Tips and Tricks
The basic command used to create volumes is "vxassist". The format is "vxassist make". The length can be specified in units of kilobytes, megabytes, or gigabytes with the suffixes k, m, or g. By default, new volumes are created from rootdg. Use "-g" to specify a different diskgroup.
To determine the maximum size that a new volume could be given particular attributes, use the "vxassist maxsize" command. For example, to determine the maximum size of a striped volume using disk01 and disk02:
Then create the volume using that length. For example: vxassist make vol01 20g layout=stripe disk01 disk02
By default, the "vxassist" command creates concatenated volumes. For example, the command "vxassist make newvol 10m" would create a concatenated volume with the length of 10 MB. To specify the disk(s) to use, add the disk name(s). For example, "vxassist make newvol 10m disk01".
To create striped volumes, add the attribute "layout=stripe". For exampke, "vxassist make newvol 10g layout=stripe disk01 disk02".
To create RAID-5 volumes, add the attribute "layout=raid5". For example, "vxassist make newvol 30g layout=raid5".
To create mirrored volumes, add the attribute "layout=mirror". For example, "vxassist make newvol 10g layout=mirror".
The "vxassist" command can be used to grow or shrink the size of volumes. Do not shrink the size of volumes below the size of the filesystem. To grow volumes, run one of the following commands:
vxassist growto
vxassist growby
Similarly, you can shrink the size of volumes:
To remove an unneeded volume, unmount any filesystems on the volume, remove any references to the volume from /etc/vfstab, stop the volume with "vxvol stop", and then run "vxedit -rf rm" or "vxassist
remove volume".
Existing volumes can be mirrored to add redundancy. To mirror existing volumes, use the following command:
To remove a mirror (more precisely, to remove one of the plexes from the volume), use the following command:
To stop volumes, use the command "vxvol stop". To stop all volumes, run the command "vxvol stopall". To restart volumes, use the command "vxrecover -s" or use the command Veritas will automatically allocate the necessary space from unused disks. The process may take some time depending on the size of the volume. When fully synchronized, the status of the snapshot mirror will change to SNAPDONE. Use the following command to monitor the progress of the snapshot:
2. Detach the snapshot and create the new read-only snapshot volume with the following command:
The period required to create the snapshot volume is shorter but it is preferred to limit I/O to the volume during the period required.
3. Clean the contents of the new snapshot volume with the following command:
4. Mount the snapshot volume, perform the backup, unmount the volume, and then remove the snapshot volume to save space with the following command:
Move the disks physically to the new system and either reboot the system so that Veritas recognizes the new disks, or use the command "vxdctl enable" to restart vxconfigd.
Import the disks with the command "vxdg import". Then restart all volumes in the disk group with the command "vxrecover -g -sb".
To rename diskgroups during deport/import, run the deport/import command with the argument "-n ". After importing the diskgroup, run the command "vxprint -hrt". The volumes that belong to the imported disk group may be DISABLED. Run the command "vxinfo "volume name" to be sure that the volumes are "startable". Then run "vxrecover -s" to enable each volume.
If the disks in question have been moved due to the crash of the original system, then they will not have been properly deported and will be locked. To unlock the disks, run the command "vxdisk clearimport" or "vxdg -C import". Be sure not to run these commands if the original system has physical access to the disks since that would allow access to the disks from multiple hosts and possibly cause data corruption.
You do not have to specify the new disk name. In that case, the volume will be moved to any available disk. For example, to move the volume called archive from disk03 to disk04, run the following command:
If one volume is particularly heavily used, you may want to convert from the default concatenation to striping. To do so, create a striped plex (mirror) of the volume and then remove the old (concatenated) plex. For example, to convert the volume called archive from concatenated to striped, run the following commands:
vxassist mirror archive layout=stripe disk02 disk03 disk04 vxplex -o rm dis archive-01
How-To Remove mirroring
To remove a mirror from a volume (i.e., to remove one of the plexes that belongs to the volume), run the following command:
Any associated subdisks will then become available for other uses. To remove the disk from Volume Manager control entirely, run the following command:
For example, "vxdisk rm c1t1d0s2".
How-To Delete Volume
To remove a volume, unmount any filesystems on the volume and run the following command:
1. Disassociate one of the mirrors from the volume to be backed up:
2. Create a new, temporary volume using the disassociated plex:
3. Start the new volume:
4. Clean the new volume before mounting:
5. Mount the new volume and perform the backup
6. Unmount the new volume
7. Stop the new volume:
8. Disassociate the plex from the new volume:
9. Reattach the plex to the original volume:
10. Delete the temporary volume:
To display the current Veritas configuration, use the following command:
To monitor the progress of tasks, use the following command:
To display information related to plexes, run the following command:
2. Stop any volumes on the disk group:
3. Deport the disk group:
4. Import the disk group:
5. Restart and resynchronize the disk group:
6. Remount any filesystems from the disk group
If you have any problems, check the status of volumes on the disk group:
Assumption: Veritas software has been installed and that rootdg has been setup by the installer with a minimum of one disk. If not, install the software now.
Use the "format" command to display available disks. If necessary, add new disks to the system and run "drvconfig; devlinks; disks" to configure the new disks. Do not partition disks to be used by Veritas.
To display disks setup for Veritas, use the command "vxdisk list".
To add more disks to the control of Veritas, use the following command:
vxdiskadd
The would be c2t0d0, for example, without the slice suffix. The vxdiskadd script will prompt for necessary information such as the name of the disk group, whether or not to initialize the new disk, etc. Rerun the command "vxdisk list" to view the new disk.
To designate an unused disk as a hot-spare disk, use the following command:
vxedit set spare=on
The would be the Veritas name for the disk, such as disk01. Use "vxdisk list" to confirm that the disk is now a dedicated hot-spare disk. To remove the disk from the dedicated hot-spare pool, use the following command:
vxedit set spare=off
By default, Veritas will name disks based on the name of the disk group. To rename a disk (for example, from disk01 to disk02), use the following command:
vxedit rename
To place a disk offline (for example, if the disk has become corrupted), run the following command:
vxdisk offline
To remove a disk from the diskgroup to which it belongs, run the following command:
vxdg [-g diskgroup name] rmdisk
To then remove that disk from Veritas control entirely, run the following command:
vxdisk rm
vxdg rmdisk
vxdg -g adddisk =
(For example, "vxdg -g ttdg adddisk ttdg01=c1t0d0".) vxdg -g adddisk =
Alternatively, you can simply remove the disk from Veritas control and then reinitialize it with "vxdiskadd". Use "vxdisk list" to confirm the new affiliation.
Every disk group requires a minimum of one disk. The simplest way to add a new diskgroup is to run the "vxdiskadd" command on an unconfigured disk, and when prompted for the name of the diskgroup to use, enter the desired name of the new diskgroup.
To display information on disk groups, run "vxdg list" or "vxdg list".
To destroy a diskgroup and reuse the disks for other purposes, run the following command:
vxdg destroy
The Volumes Tips and Tricks
The basic command used to create volumes is "vxassist". The format is "vxassist make". The length can be specified in units of kilobytes, megabytes, or gigabytes with the suffixes k, m, or g. By default, new volumes are created from rootdg. Use "-g" to specify a different diskgroup.
To determine the maximum size that a new volume could be given particular attributes, use the "vxassist maxsize" command. For example, to determine the maximum size of a striped volume using disk01 and disk02:
vxassist maxsize layout=stripe disk01 disk02
Then create the volume using that length. For example: vxassist make vol01 20g layout=stripe disk01 disk02
By default, the "vxassist" command creates concatenated volumes. For example, the command "vxassist make newvol 10m" would create a concatenated volume with the length of 10 MB. To specify the disk(s) to use, add the disk name(s). For example, "vxassist make newvol 10m disk01".
To create striped volumes, add the attribute "layout=stripe". For exampke, "vxassist make newvol 10g layout=stripe disk01 disk02".
To create RAID-5 volumes, add the attribute "layout=raid5". For example, "vxassist make newvol 30g layout=raid5".
To create mirrored volumes, add the attribute "layout=mirror". For example, "vxassist make newvol 10g layout=mirror".
The "vxassist" command can be used to grow or shrink the size of volumes. Do not shrink the size of volumes below the size of the filesystem. To grow volumes, run one of the following commands:
vxassist growto
vxassist growby
Similarly, you can shrink the size of volumes:
vxassist shrinkto
vxassist shrinkby
vxassist shrinkby
To remove an unneeded volume, unmount any filesystems on the volume, remove any references to the volume from /etc/vfstab, stop the volume with "vxvol stop", and then run "vxedit -rf rm" or "vxassist
remove volume".
Existing volumes can be mirrored to add redundancy. To mirror existing volumes, use the following command:
vxassist mirror
To remove a mirror (more precisely, to remove one of the plexes from the volume), use the following command:
vxplex -o rm
To stop volumes, use the command "vxvol stop". To stop all volumes, run the command "vxvol stopall". To restart volumes, use the command "vxrecover -s" or use the command Veritas will automatically allocate the necessary space from unused disks. The process may take some time depending on the size of the volume. When fully synchronized, the status of the snapshot mirror will change to SNAPDONE. Use the following command to monitor the progress of the snapshot:
vxtask -l list
2. Detach the snapshot and create the new read-only snapshot volume with the following command:
vxassist snapshot
The period required to create the snapshot volume is shorter but it is preferred to limit I/O to the volume during the period required.
3. Clean the contents of the new snapshot volume with the following command:
fsck -y /dev/vx/rdsk/
4. Mount the snapshot volume, perform the backup, unmount the volume, and then remove the snapshot volume to save space with the following command:
vxedit -rf rm
Diskgroups tips and Tirkcs
Diskgroups can be moved from one system to another system. On the original system, unmount any volumes in the disk group to be deported and stop them with the command "vxvol stop". Then deport the disk group with the command "vxdg deport".
Import the disks with the command "vxdg import". Then restart all volumes in the disk group with the command "vxrecover -g -sb".
To rename diskgroups during deport/import, run the deport/import command with the argument "-n ". After importing the diskgroup, run the command "vxprint -hrt". The volumes that belong to the imported disk group may be DISABLED. Run the command "vxinfo "volume name" to be sure that the volumes are "startable". Then run "vxrecover -s" to enable each volume.
If the disks in question have been moved due to the crash of the original system, then they will not have been properly deported and will be locked. To unlock the disks, run the command "vxdisk clearimport" or "vxdg -C import". Be sure not to run these commands if the original system has physical access to the disks since that would allow access to the disks from multiple hosts and possibly cause data corruption.
Performance tips and tricks
The performance of Veritas volumes can be monitored with the "vxstat" command. Reset the volume statistics with the command "vxstat -r", let the system run normally for several hours, and then run "vxstat" and check the read/write performance. If you see two or more heavily used volumes on the same physical disk, you may want to move one of the volumes to an unused disk. To do so, use the following command:
vxassist !
You do not have to specify the new disk name. In that case, the volume will be moved to any available disk. For example, to move the volume called archive from disk03 to disk04, run the following command:
vxassist move archive !disk03 disk04
If one volume is particularly heavily used, you may want to convert from the default concatenation to striping. To do so, create a striped plex (mirror) of the volume and then remove the old (concatenated) plex. For example, to convert the volume called archive from concatenated to striped, run the following commands:
How-To Remove mirroring
To remove a mirror from a volume (i.e., to remove one of the plexes that belongs to the volume), run the following command:
vxplex -o rm dis
Any associated subdisks will then become available for other uses. To remove the disk from Volume Manager control entirely, run the following command:
vxdisk rm
For example, "vxdisk rm c1t1d0s2".
How-To Delete Volume
To remove a volume, unmount any filesystems on the volume and run the following command:
vxassist remove volume
How-To Mirror Backup
The following techniques can be used to backup mirrored volumes by temporarily taking one of the mirrors offline and then reattaching the mirror to the volume once the backup has been run.
1. Disassociate one of the mirrors from the volume to be backed up:
vxplex dis
2. Create a new, temporary volume using the disassociated plex:
vxmake -g -U gen vol tempvol plex=
3. Start the new volume:
xvol start tempvol
4. Clean the new volume before mounting:
fsck -y /dev/vx/rdsk//tempvol
5. Mount the new volume and perform the backup
6. Unmount the new volume
7. Stop the new volume:
vxvol stop tempvol
8. Disassociate the plex from the new volume:
vxplex dis
9. Reattach the plex to the original volume:
xplex att
10. Delete the temporary volume:
vxedit rm tempvol
To display the current Veritas configuration, use the following command:
vxprint
To monitor the progress of tasks, use the following command:
vxtask -l list
To display information related to plexes, run the following command:
vxprint -lp
How-To Export-Deport
Disk groups can be moved from one system to another with the deport/import commands. The same technique can be used to rename a disk group by deporting the disk group with a new name.
1. Unmount any filesystems on the disk group 2. Stop any volumes on the disk group:
vxvol stop
3. Deport the disk group:
vxdg deport
4. Import the disk group:
vxdg import
5. Restart and resynchronize the disk group:
vxrecover -g -sb
6. Remount any filesystems from the disk group
If you have any problems, check the status of volumes on the disk group:
vxinfo
To rename the disk group during deport/import, use the -n argument:
vxdg deport -n
Thursday, September 1, 2011
Why Linux is so Popular ?
Here are the most popular Operating System:
Windows
Mac OS
UNIX(Linux)
Linux is an operating system - very much like UNIX - that has become very popular over the last several years.An operating system is the first piece of software that the computer executes when you turn the machine on. The operating system loads itself into memory and begins managing the resources available on the computer. It then provides those resources to other applications that the user wants to execute.
Typical services that an operating system provides include:
A task scheduler
A memory manager
A disk manager
A network manager
Other I/O services manager
Security manager
An operating system normally also provides the default user interface for the system. The standard "look" of Windows XP includes the Start button, the task bar, etc. The Mac OS provides a completely different look and feel for Macintosh computers.
Linux is as much a phenomenon as it is an operating system. To understand why Linux has become so popular, it is helpful to know a little bit about its history. The first version of UNIX was originally developed several decades ago and was used primarily as a research operating system in universities. High-powered desktop workstations from companies like Sun proliferated in the 1980s, and they were all based on UNIX. A number of companies entered the workstation field to compete against Sun: HP, IBM, Silicon Graphics, Apollo, etc. Unfortunately, each one had its own version of UNIX and this made the sale of software difficult. Windows NT was Microsoft's answer to this marketplace. NT provides the same sort of features as UNIX operating systems -- security, support for multiple CPUs, large-scale memory and disk management, etc. -- but it does it in a way that is compatible with most Windows applications.
The entry of Microsoft into the high-end workstation arena created a strange dynamic. The proprietary operating systems owned by separate companies and the lack of a central authority in the UNIX world weaken UNIX, but many people have personal problems with Microsoft. Linux stepped into this odd landscape and captured a lot of attention.
The Linux kernel, created by Linus Torvalds, was made available to the world for free. Torvalds then invited others to add to the kernel provided that they keep their contributions free. Thousands of programmers began working to enhance Linux, and the operating system grew rapidly. Because it is free and runs on PC platforms, it gained a sizeable audience among hard-core developers very quickly. Linux has a dedicated following and appeals to several different kinds of people:
People who already know UNIX
People who want to experiment with operating system principles
People who need or want a great deal of control over their operating system
People who have personal problems with Microsoft
In general, Linux is harder to manage(For user, it just blank screen) than something like Windows, but offers more flexibility and configuration options.
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