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Fstab File explaination

Posted on 2011-02-16
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Last Modified: 2012-05-11
Hi, Can somebody please explain me below fstab file. i have some questions.
1- what is anaconda ?
2- what is /dev/disk ?
3- what is first UUID , what is 2nd UUID ?
4- what is gid ?
5- what is mode ?
#
# /etc/fstab
# Created by anaconda on Fri Jan 14 15:46:25 2011
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
UUID=d46e00c6-176a-4aae-ae12-???????????? /                       ext4    defaul
ts        1 1
UUID=8da332a1-bb7f-456f-8bca-???????????? /tmp                    ext4    defaul
ts        1 2
UUID=5cd7b95a-8e80-4c86-92d5-???????????? swap                    swap    defaul
ts        0 0
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
xyzisilon:/ifs/systems/home   /home           nfs     defaults,nolock,noatime,
nodiratime     0 0
xyzisilon:/ifs/data/code   /code           nfs     defaults,nolock,noatime,nod
iratime     0 0
xyzisilon:/ifs/systems/apps   /apps           nfs     defaults,nolock,noatime,
nodiratime,fsc     0 0
xyzisilon:/ifs/systems/deadlinerepo-test      /mnt/deadlinerepo-test  nfsdefau
lts,nolock,noatime,nodiratime   0 0
xyzisilon:/ifs/jobs   /jobs   nfs     defaults,nolock,noatime,nodiratime,fsc0
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Question by:aashee
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8 Comments
 
LVL 4

Expert Comment

by:RobertParten
ID: 34910541
There isn't an easy way to explain the fstab without first getting a few basics down:

http://www.tuxfiles.org/linuxhelp/fstab.html

Read that and if you have any other questions I would not mind helping you out.
0
 
LVL 79

Expert Comment

by:arnold
ID: 34910795

source/device mount_point  filesystem_type options boot_order fsck

UUID= deals with identifying the LVM volume based on UUID (seen lvdisplay) as /, /tmp and swap partitions.
NFS (networked Filesystem)
remoteserver:/share

The options in the nfs mount point nolock (do not use lock mechanism), noatime do not update access time, nodiratime do not update directory for access time.

The link RobertParten is very informative.
0
 

Author Comment

by:aashee
ID: 34911660
Yes RobertParten link is very very useful.

i've got much deeper understand after reading that link

what is LVM volume based on UUID ? what is lvdisplay

what is lock mechanism?

what does mean by do not update directory for access time ?


what does this UUID represent and where does it calculates its value from ?UUID=d46e00c6-176a-4aae-ae12-????????????

you guys are so helpful
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LVL 4

Expert Comment

by:RobertParten
ID: 34911728
Ahh young grasshopper, this conversation could go on and on forever.

http://tldp.org/LDP/intro-linux/intro-linux.pdf

Is a GREAT read for learning about Linux. Take your time and read. Ask questions carefully. A good place to get help sometimes for small questions will be IRC (Internet Relay Chat).

I recommend downloading and IRC client and log onto the FREENODE network

irc.freenode.net

Register your nick name and join into the channel of OS you are using and you can ask small questions in real time.
0
 
LVL 79

Accepted Solution

by:
arnold earned 2000 total points
ID: 34912090
UUID is a unique identification of a partition on the local hard drive and is generated when they are created using LVM.
lvdisplay is a command that when run displays the partitions you have and their UUID.
There is no point in masqueradingthe UUID as they are unique to your system and divulge no information about you.

lock is an arbitration mechanism deals with avoiding conflict i.e. two systems trying to write into the same file.

When a file/directory is accessed, there are three records, when was the file/directory created, modified or accessed. The noatime nodiratime saves on resources by telling the system to not update those entries.  This is often done on files that are regularly access (active access such that the access time changes quickly.)
0
 

Author Comment

by:aashee
ID: 34912283
when i type lvdisplay,
it says No volume groups found .

0
 
LVL 79

Expert Comment

by:arnold
ID: 34916165
http://liquidat.wordpress.com/2007/10/15/short-tip-get-uuid-of-hard-disks/
Thought the UUID was from the LVM, but it was from the drive itself.
ls -l /dev/disk/by-uuid
0
 

Author Comment

by:aashee
ID: 34916347
i want to close it by myself
0

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