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Course materials may not be reproduced in whole or in part without the prior written permission of IBM. 5.2 Copyright IBM Corporation 2009

Unit 7

System storage overview

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Copyright IBM Corporation 2009

Unit objectives

After completing this unit, you should be able to:

Describe the terminology and concepts associated with:

Physical volumes

Volume groups

Logical volumes Physical partitions

Logical partitions

Describe how file systems and logical volumes are related

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Components of AIX storage

Managed by

Logical Volume Manager (LVM)

Physical storage

Logical storage

File systems

Directories

Files

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Traditional UNIX 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 5

Partition 4

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Benefits of the LVM

Solves noncontiguous space problems

Data can span disks

Sizes can be dynamically increased

Data can be mirrored for availability

New disks are easily added to the system

Data can be relocated

LVM (data) statistics can be collected

These tasks can be performed dynamically!

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Logical Volume Manager components

Logical

volume (LVs)

write(data);

Application

Logical

partitions (LPs)

Physical

partitions (PPs)

Volume group

Physical

volumes (PVs)

12

3456xyz

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Physical storage

Volumegroup A

Volume

group B

PV1

PV2 PV3 PV4 PV5

Physical

volume

/dev/hdiskn

PPn

PP3PP4PP5PP6

PP1PP2

-t factor Disks (PVs) PPs per PV Disks (PVs) -t factor

1 32 1016 128 1

2 16 2032 64 2

4 8 4064 32 4

8 4 8128 16 8

16 2 16256 8 16

N/A N/A 32512 4 32

N/A N/A 65024 2 64

Original volume groups Big volume groups

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Volume groups

AIX contains one mandatory Volumes Group: rootvg rootvg is created on system install

Contains the AIX Operating System

Why create new volume groups? Separate user data from operating system files.

Disaster recovery

Data portability

Data integrity and security

Volume GroupType MaxPVs Max LVs Max PPs perVG Max PPSize

Original 32 256 32512

(1016 * 32)

1 GB

Big 128 512 130048

(1016 * 128)

1 GB

Scalable 1024 4096 2097152 128 GB

rootvg datavgPV1 PV2 PV3

Volume group types: Original Big

Scalable

Limits

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Volume group descriptor area

VGDA VGDA

VGDA VGDA

VGDAVGDAVGDA

VGDAVGDA

One-disk VG

Two-disk VG Three-disk or more

VG

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Physical volumes1713192531354147

28

14202632364248

3 49 10

15 1621 2227

2833 3437 3843 4449 50

Logical Volume Manager

1713192531354147

28

14202632364248

3 49 10

15 1621 2227

2833 3437 3843 4449 50

Logical storage

1 2 3 4 1 2 3 4

Logicalvolume

Logical

partitionsLogicalvolume

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Uses of logical volumes

A logical volume may contain one of the following:

Journaled (JFS) or enhanced journaled file system (JFS2)

Journal log (/dev/hd8)

Paging space (/dev/hd6)

Boot logical volume (/dev/hd5)

Dump device

Nothing (raw logical volume)

Examples of JFS/JFS2 logical volumes:

/dev/hd1 /home

/dev/hd2 /usr/dev/hd3 /tmp

/dev/hd4 /

/dev/hd9var /var

/dev/hd10opt /opt

/dev/hd11admin /admin/dev/lv00 /myfilesystem

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What is a file system?

A file system is:

Method of storing data

Hierarchy of directories

Seven types supported:

Journaled File System (JFS)

Enhanced Journaled File System (JFS2)

CD-ROM File System (CDRFS)

DVD-ROM File System (UDFS)

Network File System (NFS)

Common Internet Filesystem (CIFS) Proc File System (PROCFS)

Different file systems are connected together throughdirectories to form the view of files that users see.

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Why have multiple file systems?

Can strategically place it on disk for improved performance

Some tasks are performed more efficiently on a file systemthan on each directory within the file system, for example, backup, move, secure an entire file system.

Can limit disk usage of users by file system through quotas Maintain integrity of the entire file system structure, for

example, if one file system is corrupted, the others are notaffected

Special security situations

Organize data and programs into groups for ease of filemanagement and better performance

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Standard file systems in AIX

home sbin opt lpp proc usr dev tftpboot var mnt etc tmp

/ (root)

hd4

hd1 hd9var hd3/ / /

hd2/libbin sbin spool adm tmp

/hd10opt

csm freeware

Note:The drawing depicts logical, not physical volumes.

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/etc/filesystems

/:dev = /dev/hd4vol = rootmount = automaticcheck = falsevfs = jfs2log = /dev/hd8type = bootfs

/home:dev = /dev/hd1vol = /homemount = truecheck = truevfs = jfs2

log = /dev/hd8/home/team01:dev = /dev/fslv00vfs = jfs2log = /dev/loglv00mount = true

options = rwaccount = false

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Mount

mountis the glue that logically connects file systems to the

directory hierarchy. File systems are associated with devices represented by special

files in/dev(the logical volume).

When a file system is mounted, the logical volume and its

contents are connected to a directory in the hierarchical treestructure.

What to

mount

Where to

mount it

# mount /dev/fslv00 /home/patsie

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Mounting over an empty directory

Before

patsieliz john

docdata.profile.exrcmyscript

After

liz john


home home

/

patsie

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Mounting over files

Before After

liz

john

liz

john



.profile

.exrcreports pgms

home home

/

patsiepatsie

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Listing file systems

# lsfsName Nodename Mount Pt VFS Size Options Auto Accounting

/dev/hd4 -- / jfs2 1966080 -- yes no

/dev/hd1 -- /home jfs2 131072 -- yes no

/dev/hd2 -- /usr jfs2 4587520 -- yes no

/dev/hd9var -- /var jfs2 655360 -- yes no

/dev/hd3 -- /tmp jfs2 393216 -- yes no

/proc -- /proc procfs -- -- yes no

/dev/hd10opt -- /opt jfs2 524288 -- yes no/dev/hd11admin -- /admin jfs2 262144 -- yes no

/dev/fslv00 -- /db2 jfs2 262144 rw no no

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Listing logical volume information

List all logical volumes for a volume group

# lsvg -l rootvg

rootvg:

LV NAME TYPE LPs PPs PVs LV STATE MOUNT POINT

hd5 boot 1 2 2 closed/syncd N/A

hd6 paging 8 16 2 open/syncd N/Ahd8 jfs2log 1 2 2 open/syncd N/A

hd4 jfs2 15 30 2 open/syncd /

hd2 jfs2 35 70 2 open/syncd /usr

hd9var jfs2 5 10 2 open/syncd /var

hd3 jfs2 3 6 2 open/syncd /tmp

hd1 jfs2 1 2 2 open/syncd /home

loglv00 jfs2log 1 2 2 closed/syncd N/A

hd11admin jfs 2 4 2 open/syncd /adminfslv00 jfs2 2 4 2 closed/syncd /db2

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Checkpoint (1 of 3)

VGDA

1. V______ G______

D ______ A______

2. P______ P ______

3. L_____ P______

4. L______ V_______

6. P______ V______

5. V______ G______

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Checkpoint solutions (1 of 3)

VGDA

1. Volume Group___

Descriptor Area__

2. Physical Partition

3. Logical Partition

4. Logical Volume

6. Physical Volume

5. Volume Group

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Checkpoint (2 of 3)

7. How many different physical partition (PP) sizes can be set within

a single VG? ____________

8. By default, how big are PPs?____________________________________________

____________________________________________

9. How many volume groups (VGs) can a physical volume (PV)belong to?

a) Depends on what you specify through SMIT

b) Only one

c) As many VGs as exist on the system

10. True or False: All VGDA information on your system is identical,regardless of how many volume groups (VGs) exist.

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7. How many different physical partition (PP) sizes can be set within

a single VG? One

8. By default, how big are PPs? Traditionally 4 MB, but LVMchooses an optimal size based on the #PPs/PV and the sizeof largest PV in the VG.

9. How many volume groups (VGs) can a physical volume (PV)belong to?

a) Depends on what you specify through SMIT

b) Only one

c) As many VGs as exist on the system

10. True or False: All VGDA information on your system is identical,regardless of how many volume groups (VGs) exist. All VGDAswithin a VG are the same.

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Checkpoint (3 of 3)

Use the following output to answer the questions below:

11. With which logical volume is the /home file system associated?_____________________________________________________

12. What type of file systems are being displayed?_____________________________________________________

13. What is the mount point for the file system located on the /dev/hd4 logicalvolume? _____________________________________________

14. Which file system is used primarily to hold user data and home directories?_____________________________________________________


/dev/hd4 -- / jfs2 294912 -- yes no





/dev/hd10opt -- /opt jfs2 163840 -- yes no

/dev/cd0 -- /infocd cdrfs ro yes no

/dev/lv00 -- /home/john jfs2 32768 rw yes no

/dev/hd11admin -- /admin jfs2 262144 -- yes no

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Use the following output to answer the questions below:

11. With which logical volume is the /home file system associated?/dev/hd1

12. What type of file systems are being displayed?Enhanced journaled file systems (JFS2), and CD-ROM (CDRFS)

13. What is the mount point for the file system located on the /dev/hd4 logicalvolume?

/

14. Which file system is used primarily to hold user data and home directories?

/home


/dev/hd4 -- / jfs2 294912 -- yes no





/dev/hd10opt -- /opt jfs2 163840 -- yes no

/dev/cd0 -- /infocd cdrfs ro yes no

/dev/lv00 -- /home/john jfs2 32768 rw yes no

/dev/hd11admin-- /admin jfs2 262144 -- yes no

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Exercise 7

System

storage

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Unit summary

Having completed this unit, you should be able to:

Describe the terminology and concepts associated with:

Physical volumes

Volume groups

Logical volumes

Physical partitions

Logical partitions

Describe how file systems and logical volumes are

related

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