Storage Management in Linux OS.ppt
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This document discusses storage management in Linux. It covers disk partitioning, file systems, logical volume management (LVM), and some common tools. It describes: 1. How hard disks can be partitioned into primary, extended, and logical partitions using tools like fdisk and parted. 2. The components of storage including files, directories, file systems, and how logical and physical storage relate. 3. How LVM allows logical volumes to span physical disks, be dynamically resized, and helps solve issues with traditional partitioning. 4. Common commands to manage physical volumes, volume groups, and logical volumes with LVM.
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Storage Management in Linux OS.ppt
- 2. Storage Basic • Devices • Partitions
- 3. Partitions types : • Physical • Extended • Logical
- 4. Components of storage • Files • Directories • File systems • Logical storage • Physical storage • Logical Volume Manager (LVM)
- 5. Hard disk partitions • IDE and SCSI hard disks can be partitioned • Maximum of four primary partitions • One primary partition may be an extended partition • An extended partition can hold an unlimited amount of logical partitions (Linux: max 59 for IDE, 11 for SCSI) master boot record partition table Windows Linux / Linux /home Linux swap sda: The first sector of the disk contains the MBR and Partition Table sda1: First primary partition holds a Windows filesystem sda2: Second primary partition is an extended partition and holds three logical partitions sda5: First logical partition holds a Linux filesystem that will be mounted as / sda6: Second logical partition holds a Linux filesystem that will be mounted as /home sda7: Third logical partition holds a Linux swap space
- 6. Partitioning tools • fdisk – Virtually every PC OS comes with a tool fdisk to create partitions for that OS • Linux, Windows, and so forth • parted – GPLed Linux program, available at www.gnu.org – Can create/resize/move/delete partitions • GParted, QTParted – GUI utilities that use GNU Parted – Can create/resize/move/delete partitions • Disk Druid and others – Partitioning program integrated in Linux install program
- 7. Steps for creating and using partitions in Linux Step 1: Creating a partition Step 2: Formatting a partition Step 3: Mounting a partition
- 8. fdisk utility fdisk also known as format disk is a dialog-driven command in Linux used for creating and manipulating disk partition table. It is used for the view, create, delete, change, resize, copy and move partitions on a hard drive using the dialog-driven interface. fdisk allows you to create a maximum of four primary partitions and the number of logical partition depends on the size of the hard disk you are using. It allows the user: • To Create space for new partitions. • Organizing space for new drives. • Re-organizing old drives. • Copying or Moving data to new disks(partitions).
- 9. • Syntax : # fdisk [options] device View All Disk Partitions: # fdisk –l View Partition on a Specific Disk: # fdisk –l /dev/sda • To check either disk is detected or not # dmesg | grep sd
- 10. 1. View all Disk Partitions in Linux The following basic command list all existing disk partition on your system. The ‘-l‘ argument stand for (listing all partitions) is used with fdisk command to view all available partitions on Linux. The partitions are displayed by their device’s names. For example: /dev/sda, /dev/sdb or /dev/sdc.
- 11. 2. View Specific Disk Partition in Linux • To view all partitions of specific hard disk use the option ‘-l‘ with device name. For example, the following command will display all disk partitions of device /dev/sda. If you’ve different device names, simple write device name as /dev/sdb or /dev/sdc.
- 12. 3. Check all Available fdisk Commands • If you would like to view all commands which are available for fdisk. Simply use the following command by mentioning the hard disk name such as /dev/sda as shown below. The following command will give you output similar to below.
- 13. • Type ‘m‘ to see the list of all available commands of fdisk which can be operated on /dev/sda hard disk. After, I enter ‘m‘ on the screen, you will see the all available options for fdisk that you can be used on the /dev/sda device.
- 15. 4. Print all Partition Table in Linux • To print all partition table of hard disk, you must be on command mode of specific hard disk say /dev/sda. From the command mode, enter ‘p‘ instead of ‘m‘ as we did earlier. As I enter ‘p‘, it will print the specific /dev/sda partition table.
- 16. 6. Create a New Partition in Linux • If you’ve free space left on one of your device say /dev/sda and would like to create a new partition under it. Then you must be in fdisk command mode of /dev/sda. Type the following command to enter into command mode of specific hard disk. After entering in command mode, now press “n” command to create a new partition under /dev/sda with specific size. This can be demonstrated with the help of following given output.
- 17. While creating a new partition, it will ask you two options ‘extended‘ or ‘primary‘ partition creation. Press ‘e‘ for extended partition and ‘p‘ for primary partition. Then it will ask you to enter following two inputs. • First cylinder number of the partition to be create. • Last cylinder number of the partition to be created (Last cylinder, +cylinders or +size). You can enter the size of cylinder by adding “+5000M” in last cylinder. Here, ‘+‘ means addition and 5000M means size of new partition (i.e 5000MB). Please keep in mind that after creating a new partition, you should run ‘w‘ command to alter and save new changes to partition table and finally reboot your system to verify newly created partition.
- 18. 7. How to Check Size of a Partition in Linux • By default, fdisk command shows the boot flag (i.e. ‘*‘) symbol on first partition. If you want to enable or disable boot flag on a specific partition, do the following steps. • Press ‘p‘ command to view the current partition table, you see there is a boot flag (asterisk (*) symbol in orange color) on /dev/sda1 disk as shown below.
- 19. • Next enter command ‘a‘ to disable boot flag, then enter partition number ‘1‘ as (i.e. /dev/sda1) in my case. This will disable boot flag on the partition /dev/sda1. This will remove the asterisk (*) flag.
- 20. 6. Delete a Hard Disk Partition To delete a partition for the hard disk and free up space occupied by that partition for example /dev/sdb. Go to the command menu using following: $ sudo fdisk /dev/sda and then type d to go to the delete partition menu. It will prompt the partition number you want to delete(type the number).
- 21. Formatting a Partition in Linux
- 22. File System in Linux • Types of file system
- 23. • To create an ext file system use : # mkfs.ext2 /dev/sdb6 # mkfs.ext3 /dev/sdb6 # mkfs.ext4 /dev/sdb6 • To create xfs file system install package xfsprogs: # yum install xfsprogs # mkfs.xfs /dev/sdb6 • To create jfs file system install package jfsutils : # yum install jfsutils # mkfs.jfs /dev/sdb6 Creating file System on partation
- 24. Creating swap partition • To create and activate swap partition # mkswap /dev/sdb5 To activate swap partition # swapon /dev/sdb5 To check swap partition is activated or not : # dmesg | tail –n 1 or use # free -m
- 25. To tune file system • Use tune2fs tool # tune2fs # tune2fs –l /dev/sdb6 # tune2fs [options] <partition name> # tune2fs -c 0 –m 0 /dev/sdb6
- 26. Mounting a partition: • Create directory under /mnt directory #mkdir /mnt/data • Use mount command to mount partition to a created directory under /mnt # mount /dev/sdb6 /mnt/data • Use following commands to check either partition is mounted or not #df #dmesg # mount
- 27. Unmounting file system • Use umount command # umount /mnt/data • To check whether any links are open use: # lsof /mnt/data 6
- 28. Auto mounting a partation • For auto mounting make entry into /etc/fstab file •
- 29. Traditional disk storage PROBLEMS: • Fixed partitions • Expanding size of the partition • Limitation on size of a file system and a file • Contiguous data requirement • Time and effort required in planning ahead Partition 1 Partition 2 Partition 3 Partition 4 Partition 5
- 30. Benefits of the LVM(Logical Volumes Management) • Logical volumes solve noncontiguous space problems • Logical volumes can span disks • Logical volume sizes can be dynamically increased • Logical volumes can be mirrored • Physical volumes are easily added to the system • Logical volumes can be relocated • Volume group and logical volume statistics can be collected These tasks can be performed dynamically!
- 31. Logical volume management • Logical volume management solves the disadvantages of traditional disk storage: – One or more physical volumes (hard disks, partitions) are assigned to a volume group (VG) – All physical volumes (PV) are split into physical extents (PE) of identical size (default 4 MB) – PEs in a VG can be combined into logical volumes (LV), which can be used like any block device • An LV can span multiple disks • To increase the size of an LV, add PEs • To increase the size of a VG, add PVs
- 32. Logical volume management on Linux PE PE PE PE PE PE PE PE PE PE PE PE PE PE PE PE PE PE volume group physical volume (hard disk or partition) physical volume (hard disk or partition) logical volume
- 33. LVM has three layers : • Bottom layer : Physical volumes • Middle layer : Volume group • Top layer : Logical volume
- 34. Commands for Physical Volume & Volume Group: • For Physical Volume : # pvcreate # pvremove # pvdisplay / pvs • For Volume Group : # vgcreate # vgremove # vgextend # vgreduce #vgdisplay / vgs
- 35. 1. Creating Groups and Volumes 1. Creating Physical volume : # pvcreate /dev/sdb6 • To display all the physical volumes created : # pvs 2. Now create Volume Group : # vgs - to check available groups Create new Volume group : # vgcreate mygrp /dev/sdb6 3. Extend or reduce volume group # vgextend vg_linuxhost /dev/sdb6 # vgreduce vg_linuxhost /dev/sdb6
- 36. 2. Creating Logical Volume : • Commands : # lvcreate # lvremove # lvextend # lvreduce # lvdisplay / lvs • Create new logical volume : # lvcreate - -name mylv1 - - size 2G mygrp • Expanding logical volume : # lvextend - -size +2G /dev/mygrp/mylv1 • Reducing the size : # lvreduce - - size 2G /dev/mygrp/mylv1
- 37. LVM implementation overview • Add hard disks and/or create partitions (type 0x8e) on existing hard disks • Initialize physical volumes (disks or partitions) # pvcreate /dev/sda3 # pvcreate /dev/sdb • Create volume group vg00 with physical volumes # vgcreate vg00 /dev/sda3 /dev/sdb • Create logical volume lv00 in volume group # lvcreate -L 50M -n lv00 vg00 • Can now use /dev/vg00/lv00 as block device
- 38. Recovering from Failure • File system and auto recovering tools • Ext2 ,Ext3, Ext4 -- e2fsck • XFS File system -- xfs_repair • JFS File System -- jfs_fsck