QUOTAS
To set up quota
1.vim /etc/fstab
LABEL=/home /home ext3 defaults,usrquota 1 2
2.mount -a
3.mount
4.mount -o remount /home
5.mount
6.ls /home
7.quotacheck -cufmg /home
8.ls /home
9.quotaon /home
a> To Set quota for user limiting his block size (BLOCKS)
Set 80 as soft (min), and 120 as hard (max)
blocks=56
soft =blocks + soft(min) ex: 56 + 80
hard =blocks + hard(min) ex: 56 + 120
1.edquota -u suma (edit the blocks of file as given below)
Filesystem blocks soft hard inodes soft hard
/dev/sda7 56 136 176 7 10 12
2.su - suma
$> dd if=/dev/zero of=/home/suma/xyz bs=1024 count=80 //Warn
$> dd if=/dev/zero of=/home/suma/xyz bs=1024 count=120 //Stop
$> ctrl d
3.repquota -t /home
b> To Set quota for user limiting his num of files (INODES)
Set 10 as soft (min),and 12 as hard (max)
1.edquota -u raju (edit the inodes of file as given below)
Filesystem blocks soft hard inodes soft hard
/dev/sda7 56 0 0 7 10 12
2.su - raju
$> touch 1 2 3
$> ls -a |wc -l //Warns
$> touch 4 5
$> ls -a |wc -l //Stop
$> ctrl d
3. repquota -t /home
RAID (redundant array of indepedent disks)
1. raid 0 ->stripping
2. raid 1 ->mirroring
3. raid 2 onwards ->parity check
TO CREATE RAID
1. fdisk /dev/sda ->create 3 partitons and label as fd
2. partprobe
3. fdisk -l
4. mdadm -C /dev/md0 -n 2 -l 1 /dev/sda8 /dev/sda9 ->create raid device
where n ->num of device l ->raid level
5. cat /proc/mdstat ->status of raid device
6. mkfs.ext3 /dev/md0 ->format raid
7. mkdir /raid
8. mount /dev/md0 /raid ->mount raid
9. cp /etc/* /raid ->put some contents to raid dir
10.ls /raid/
11.mount
12.df -h
13.vim /etc/fstab ->mount raid permanently
/dev/md0 /raid ext3 defaults 1 2 (Add this line to /etc/fstab)
14.mount -a
TO VERIFY RAID
1. cat /proc/mdstat -->status of raid device
2. umount /raid
3. mdadm --stop /dev/md0 -->stop raid device
4. umount /raid
5. cat /proc/mdstat
6. mkdir /test1 -->create dir for mounting raid partitions
7. mkdir /test2
8. mount /dev/sda8 /test1 --> mount partiton on dir
9. mount /dev/sda9 /test2 10.ls /test1
11.ls /test2
12.umount /test1 -->umount the partitions
13.umount /test2
14.mdadm --assemble /dev/md0 /dev/sda8 /dev/sda9 -->assemble partitions 15.cat /proc/mdstat
16.mount /dev/md0 /raid --> mount back the raid
17.cat /proc/mdstat
TO RECOVER A FAILED PARTITION
1. cat /proc/mdstat
2. mdadm --fail /dev/md0 /dev/sda8 //Fail a partition
3. cat /proc/mdstat
4. mdadm --add /dev/md0 /dev/sda10 //Add a partition
5. mdadm --remove /dev/md0 /dev/sda8 //Remove faulty partition
6. cat /proc/mdstat
TO REMOVE THE CONFIGURED RAID
1. vim /etc/fstab ->Remove raid entries from /etc/fstab
2. umount /dev/md0 ->unmounting the raid device
3. mdadm --stop /dev/md0 ->Stop the raid device
4. fdisk /dev/hda ->Delete the partitions
FIELDS OF /ETC/FSTAB
1.partition or label of partition
2.Directory to mount the partition
3.file system type
4.Defaults (rw,ro,acl,quota)
5.Dump (backup) 1->Take backup 0->dont take backup
6.File system check 1->first priority 2 ->second priority
0->Dont check file system
a>. TO TAKE BACK UP OF PARTITION USING DUMP COMMAND
1. dump -0uf 123 /boot ->Take backup of /boot in 123 file
2. du -h /boot/ ->check space of /boot and 123
3. du -h 123
4. mkdir /boot/extra ->add some more contents to /boot dir
5. cp /etc/* /boot/extra
6. du -h /boot/extra/
7. dump -1uf 456 /boot ->Again take backup of only newly added contents
8. du -h 456
9.du -h /boot/extra/
TO RESTORE BACK
1.cd abc ->go to dir where you want to restore
2.restore -rf /456 ->where /456 is place where we took backup
b>. TO TAKE BACK UP USING TAR COMMAND
1.tar -cvf backup file1 file2 file3 ->c-create v-verbose f-file,take
backup of file1 to file3 in backup file
2.tar -tvf backup ->t-list num of files backed up
3.tar -xvf backup ->x-extract files backed up in pwd.
4.tar -rvf backup file4 file5 ->r-append more files to backed up file
5.tar -xvf backup -C /var ->Extract files inside /var dir
To uncompress and extract a file gzip file
1.gzip backup ->compress the file
2. tar zxvf backup ->uncompress + extract the file
To uncompress and extract a file bzip2 file
1.bzip2 backup ->compress the file
2. tar jxvf backup ->uncompress + extract the file
LVM (LOGICAL VOLUME MANAGER)
1. TO CREATE LVM
1.fdisk /dev/sda ->create 3 partitions + label to 8e
2.partprobe
3.fdisk -l
4.pvcreate /dev/sda8 /dev/sda9
5.pvdisplay /dev/sda8
6.pvdisplay /dev/sda9
7.vgcreate vg0 /dev/sda8 /dev/sda9
8.vgdisplay
9.lvcreate -L +200M -n /dev/vg0/home1
10.lvdisplay /dev/vg0/home1
11.lvcreate -L +300M -n /dev/vg0/var1
12.lvdisplay /dev/vg0/var1
13.mkfs.ext3 /dev/vg0/var1
14 mkfs.ext3 /dev/vg0/home1
15.mkdir /home1
16.mkdir /var1
17.mount /dev/vg0/home1 /home1
18.mount /dev/vg0/var1 /var1
19.cp /etc/a* /home1
20.cp /etc/b* /var1
21.vim /etc/fstab
/dev/vg0/var1 /var1 ext3 defaults 1 2
/dev/vg0/home1 /home1 ext3 defaults 1 2
22.mount -a
TO EXTEND LVM
1.lvdisplay /dev/vg0/home1
2.lvextend -L +200M /dev/vg0/home1
3.ls /home1
4.resize2fs /dev/vg0/home1
5.ls /home1
TO REDUCE LVM
1. lvdisplay
2. umount /var1
3. e2fsck -f /dev/vg0/var1
4. resize2fs /dev/vg0/var1 100M
5. lvreduce -L -100M -n /dev/vg0/var1
6. mount /dev/vg0/var1 /var1
7. df -h
LVM SNAPSHOT
1. lvcreate -L 200M -s -n lv2 /dev/llc/lv1
TO EXTEND PV
1.pvcreate /dev/sda10
2.pvdisplay
TO EXTEND VG
1.vgextend vg0 /dev/sda10
2.vgdisplay vg0
TO REDUCE VG
1.vgreduce vg0 /dev/sda10
2.vgdisplay
TO REDUCE PV
1.pvremove /dev/sda10
2.pvdisplay
REMOVE LVM
1.lvdisplay
2.umount /dev/vg0/home1
3.umount /dev/vg0/var1
4.vim /etc/fstab
5.lvremove /dev/vg0/home1
6.lvremove /dev/vg0/var1
7.lvdisplay
REMOVE VG
1.vgdisplay
2.vgremove /dev/vg0
3.vgdisplay
REMOVE PV
1.pvdisplay
2.pvremove /dev/sda9
3.pvremove /dev/sda8
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