Superblock : File System size and indentification, Free list, fragment size, nbpi.
Inodes: File size, ownership, permissions, pointers to data blocks.
Blocks: Data blocks contain data and Indirect block contain pointers to data blocks.
Journaled file systems are built within logical volumes. Because journaled file systems exist within logical volumes, the size of the file system always multiples of the logical partition size for that logical volume (for example, 4 MB). An individual file within a file system will by default have units allocated to it in blocks of 4096 bytes. (This may change if you have implemented fragmentation or large files – to be discussed later.)
Some unix commands often report file sizes in units of 512 bytes to remain compatible with other UNIX file systems. This is independent of the actual unit of allocation. The first addressable logical block on the file system is the superblock. The superblock contains information such as the file system name, size, number of inodes, date/time of creation.
The superblock is critical to the file system and if corrupted, prevents the file system from mounting. For this reason a backup copy of the superblock is always written in block 31. Uempty Immediately following the superblock are inodes which contain identifying information for files such as the file type, size, permissions, user/group/owner, create/modification and last
access dates. They also contain pointers to the data block for fragment addresses which hold the data. For larger files the system creates sets of indirect blocks filled with data block addresses to point to the data block or fragments which hold the data.
NOTE: This is the version for Enterprise Linux AS 5. Your version may be different.
An alternative to installing this package manually in Red Hat Enterprise Linux (ES or AS) 5 or greater is to use the “Add/Remove Applications” menu item in the “System Settings” menu. In the details for the “Network Servers” package list, the iscsi-initiator-utils is one of the packages listed. This same choice is available in the same location during the initial install of Red Hat, so this can also be done at that time.
Once installed, there will be a file in the /etc directory named iscsi.conf. If this file does not exist this may indicate a problem with the installation. This file can be created with the following minimal entries:
This needs to be set to the Group IP Address of your UIT Array.
For the initiator to receive Vendor Specific async events from the target.
To globally specify that all discovery sessions be kept open.
Within the iscsi.conf file itself there are many more options available that can be set. You can look through the iscsi.conf file for information on what these variables are and what they are used for.
Once these values are either placed in a newly created /etc/iscsi.conf file, or the respective lines are uncommented and edited where necessary, the iscsi service can be started:
# service iscsi start
To verify that the iscsi service will be started at boot time, the chkconfig command can be used as follows:
# chkconfig –list iscsi
iscsi 0:off 1:off 2:off 3:off 4:off 5:off 6:off
By default, the newly added iscsi initiator is not enabled at boot which is the reason for each of the run levels listed to have the service set to off. To enable this at boot, again use the chkconfig command as follows:
# chkconfig –add iscsi
# chkconfig iscsi on
The above two commands first checks to be sure there are the necessary scripts to start and stop the service, then it sets this service to be on for the appropriate runlevels.
Then check to be sure the changes took effect:
# chkconfig –list iscsi
iscsi 0:off 1:off 2:on 3:on 4:on 5:on 6:off
To verify that you can see your iscsi devices, you can run the following command:
As can be seen in the example iscsi-ls –l output above, the device in question is mapped to the /dev/sdc device.
Linux-iscsi Sourceforge Initiator:
If you are not running the required update of Red Hat Linux to have their precompiled iSCSI Initiator, you can try to compile the iSCSI Initiator supplied by the Sourceforge linux-iscsi project.
Beyond the required kernel revision as noted above, all development packages need to be installed for the compiling of the initiator as well as the kernel sources. The easiest way to install these items is to us the “Add/Remove Applications” in the “System Settings Menu” from within the Desktop GUI. Depending on the version of Red Hat you are running will determine what you select to be installed:
Red Hat AS 3:
Development Tools (Default packages have all required packages)
Kernel Development (Again, default is fine)
Red Hat AS 4:
Development Tools (Default packages have all required packages)
NOTE: If there is no Kernel Development choice, the Kernel Source files need to be found and installed prior to compilation.
Once these OS packages are installed, it should be as easy as getting the source package from the Sourceforge linux-iscsi project, then making the initiator. Refer to the README file that comes with the source for detailed instructions on how to make the initiator. If there are problems compiling the initiator, check the linux-iscsi Sourceforge project for assistance. You are able to search and post to their mailing lists to get information and assistance with this product.
Persistent Device naming:
Devices using the Red Hat software initiators do not have a persistent naming scheme, but a few ways to setup Persistent Naming for the different versions of Red Hat are as follows:
Red Hat Enterprise Linux (ES or AS) 3:
Devlabel (see the devlabel man page):
This will only work on Red Hat kernel’s 2.4.x.
Use devlabel to setup symlinks from known names to the current device name.
A basic add command to setup a devlabel link is as follows:
This is only available on Red Hat EL 4/Kernel 2.6.*
This creates device links to the device files when the device nodes are created. Udev uses a rules file (see man udev) to determine what the link names or device names it should create for different devices.
This is the least elegant of the solutions to configure and there is no straightforward example to provide on how this needs to be setup.
Red Hat may be able to provide additional information on persistent device naming for iSCSI devices using their iSCSI initiator with udev.
Both Red Hat Enterprise Linux 3 and 4:
Use filesystem LABELs (see the e2label man page):
This will work on all ext2/3 filesystem partitions.
Place an ext2/3 filesystem label on your filesystem partition. Once the Label has been added, use the LABEL identifier to identify the filesystem you want to mount in the fstab (man fstab and/or man mount). Following is an example of using the e2label command and what a resulting line in the fstab file would look like:
# e2label /dev/sdc1 EMC
must run the following command from the global zone
prctl –n zone.cpu-shares –v <value> -r –i zone <zone number>
h2 style=”MARGIN: 12pt 0in 3pt”>=Arial>Notes
You can install apps either at a global or non-global level.Caveat, user’s will be unable to install packages to /usr/local at a non-global level unless we create /usr/local as a filesystem to mount. But then, we must effectively cover anything in the global /usr/local.Just be aware.
Hulu, a streaming video site created by NBC Universal and News Corp., for yourself. The U.S.-only site features a few full-length movies,and a good number of clips and full episodes of shows like Family.
Now, How to download hulu movies ?
RipTiger is an very good program that allows you to download videos from Hulu.com. But not only download, it helps to convert videos so I can share it with my friends. RipTiger can copy all your downloaded videos to iPod and any other portable player!
How I use it:
1. Install and launch RipTiger (better Ultimate edition, because it can convert downloaded video).
2. Open hulu.com in Internet Explorer and RipTiger automatically starts downloading.
3. When downloading is finished, Riptiger Ultimate starts conversion to MPEG4 (because I want to put the video into my iPod).
4. When clicking to iPod icon videos are copied to iPod.
TMZ acquired five photos of former NFL QB Steve McNair vacationing with Sahel Kazemi, the woman who likely murdered him and then killed herself early Saturday.
Former Titans Quarterback Steve McNair and Sahel Kazemi, who were shot dead in what appears to be a murder/suicide, had been dating for five months and had been planning to tie the knot as soon as the 36 year-old got a divorce from his wife Mechelle McNair.
Steve and Sahel were often seen together, they spent several mini-vacations together (photos below) and they were reportedly smitten with each other. We can clearly see in these photos, the couple had great chemistry and were having a good time.