AIX Concepts

AIX

LVM:

VG: One or more PVs can make up a VG.

Within each volume group one or more logical volumes can be defined.

VGDA(Volume group descriptor area) is an area on the disk that contains information pertinent to the vg that the PV belongs to. It also includes information about the properties and status of all physical and logical volumes that are part of the vg.

VGSA(Volume group status area) is used to describe the state of all PPs from all physical volumes within a volume group. VGSA indicates if a physical partition contains accurate or stale information.

LVCB(Logical volume control block) contains important information about the logical volume, such as the no. of logical partitions or disk allocation policy.

VG type Max Pv’s Max LV’s Max PP’s/VG Max PP Size

Normal 32 256 32512 1G

BIG 128 512 130048 1G

Scalable 1024 4096 2097152 128G

PVIDs stored in ODM.

Creating PVID : chdev –l hdisk3 –a pv=yes

Clear the PVID : chdev –l hdisk3 –a pv=clear.

Display the allocation PP’s to LV’s : lspv –p hdisk0

Display the layout of a PV: lspv –M hdisk0

Disabling partition allocation for a physical volume : chpv –an hdisk2 : Allocatable=no

Enabling partition allocation for a physical volume : chpv –ay hdisk2 : Allocatable = yes

Change the disk to unavailable : chpv –vr hdisk2 : PV state = removed

Change the disk to available : chpv –va hdisk2 : PV state = active

Clean the boot record : chpv –c hdisk1

To define hdsik3 as a hotspare : chpv –hy hdisk3

To remove hdisk3 as a hotspare : chpv –hn hdisk3

Migrating ttwo disks : migratepv hdisk1 hdisk2

Migrate only PPS that belongs to particular LV : migratepv –l testlv hdisk1 hdisk5

Move data from one partition located on a physical disk to another physical partition on a different disk: migratelp testlv/1/2 hdisk5/123

Logical track group(LTG) size is the maximum allowed transfer size for an IO disk operation. Lquerypv –M hdisk0

VOLUME GROUPS

For each VG, two device driver files are created under /dev.

Creating VG : mkvg –y vg1 –s64 –v99 hdisk4

Creating the Big VG : mkvg –B –y vg1 –s 128 –f –n –V 101 hdisk2

Creating a scalable VG: mkvg –S –y vg1 –s 128 –f hdisk3 hdisk4 hdisk5

Adding disks that requires more than 1016 PP’s/PV using chvg –t 2 VG1

Information about a VG read from a VGDA located on a disk: lsvg –n VG1

Change the auto vary on flag for VG : chvg –ay newvg

Change the auto vary off flag for VG: chvg –an newvg

Quorum ensures data integrity in the event of disk failure. A quorum is a state in which 51 percent or more of the PVs in a VG accessible. When quorum is lost, the VG varies itself off.

Turn off the quorum : chvg –Qn testvg

Turn on the quorum : chvg –Qy testvg

To change the maximum no of PPs per PV : chvg –t 16 testvg.

To change the Normal VG to scalable vg : 1. Varyoffvg ttt 2. chvg –G ttt 3. varyonvg ttt

Change the LTG size : chvg –L 128 testvg à VG’s are created with a variable logical track group size.

Hot Spare: In Physical volume all PP’s shou;d be free. PP located on a failing disk will be copied from its mirror copy to one or more disks from the hot spare pool.

Designate hdisk4 as hot spare: chpv –hy hdisk4

Migrate data from a failing disk to spare disk: Chvg –hy vg;

Change synchronization policy : chvg –sy testvg; synchronization policy controls automatic synchronization of stale partitions within the VG.

Change the maximum no. of pps within a VG: chvg –P 2048 testvg

Change maximum no.of LVs/VG : chvg –v 4096 testvg.

How to remove the VG lock : chvg –u

Extending a volume group : extendvg testvg hdisk3; If PVID is available use extendvg –f testvg hdisk3

Reducing the disk from vg : reducevg testvg hdisk3

Synchronize the ODM information : synclvodm testvg

To move the data from one system to another use the exportvg command. The exportvg command only removes VG definition from the ODM and does not delete any data from physical disk. : exportvg testvg

Importvg : Recreating the reference to the VG data and making that data available.. This command reads the VGDA of one of the PV that are part of the VG. It uses redefinevg to find all other disks that belong to the VG. It will add corresponding entries into the ODM database and update /etc/filesystems with new values. importvg –y testvg hdisk7

• Server A: lsvg –l app1vg
• Server A: umount /app1
• Server A: Varyoffvg app1vg
• Server B: lspv|grep app1vg
• Server B: exportvg app1vg
• Server B: importvg –y app1vg –n V90 vpath0
• Chvg –a n app1vg
• Varyoffvg app1vg

Varying on a volume group : varyonvg testvg

Varying off a volume group : varyoffvg testvg

Reorganizing a volume group : This command is ued to reorganize physical partitions within a VG. The PP’s will be rearranged on the disks according to the intra-physical and inter-physical policy. reorgvg testvg.

Synchronize the VG : syncvg –v testvg ; syncvg –p hdisk4 hdisk5

Mirroring a volume group : lsvg –p rootvg; extendvg rootvg hdisk1; mirrorvg rootvg; bosboot –ad /dev/hdisk1; bootlist –m normal hdisk0 hdisk1

Splitting a volume group : splitvg –y newvg –c 1 testvg

Rejoin the two copies : joinvg testvg

Logical Volumes:

Create LV : mklv –y lv3 –t jfs2 –a im testvg 10 hdisk5

Remove LV : umount /fs1, rmlv lv1

Delete all data belonging to logical volume lv1 on physical volume hdisk7: rmlv –p hdsik7 lv1

Display the no. of logical partitions and their corresponding physical partitions: lslv –m lv1

Display information about logical volume testlv read from VGDA located on hdisk6: lslv –n hdisk6 testlv

Display the LVCB : getlvcb –AT lv1

Increasing the size of LV : extendlv –a ie –ex lv1 3 hdisk5 hdisk6

Copying a LV : cplv –v dumpvg –y lv8 lv1

Creating copies of LV : mklvcopy –k lv1 3 hdisk7 &

Splitting a LV : umount /fs1; splitlvcopy –y copylv testlv 2

Removing a copy of LV : rmlvcopy testlv 2 hdisk6

Changing maximum no.of logical partitions to 1000: chlv –x 1000 lv1

Installation :

New and complete overwrite installation : For new machine, Overwrite the existing one, reassign your hard disks

Migration: upgrade AIX versions from 5.2 to 5.3. This method preserves most file systems, including root volume group.

Preservation installation : If you want to preserve the user data.. use /etc/preserve.list. This installation overwrites /usr, /tmp,/var and / file systems by default. /etc/filesystems file is listed by default.

TCB:

• To check the tcb is installed or not: /usr/bin/tcbck.
• By installing a system with the TCB option, you enable the trusted path, trusted shell, trusted processes and system integrity checking.
• Every device is part of TCB and every fle in the /dev directory is monitored by the TCB.
• Critical information about so many files storing in /etc/security/sysck.cfg file
• You can enable TCB anly at installation time

Installation steps : Through HMC à activate à override the boot mode to SMS.

Without hmc à After POST à hear the 2 beeps à press 1.

Insert the AIX 5L CD1. à select boot options(NO:5)àSelect install / Boot devise(Option1)à select CD/DVDà select SCSIà select the normal bootà exit from SMSàSystem boots from mediaàChoose languageàChange/show installation settingsàNew and complete overriteàselect harddiskàInstall optionsàenter to confirmàAfter installation system reboots automatically

Erase a hard disk à using diag command

Alternate Disk Installation:

• Cloning the current running rootvg to an alternate disk
• Installing a mksysb image on another disk.

Alt_disk_copy: Creates copies of rootvg on an alternate set of disks.

Alt_disk_mksysb: Installs an existing mksysb on an alternate set of disks.

Alt_rootvg_op: Performs wake, sleep and customize operations.

Alternate mksysb installation: smitty alt_mksysb

Alternate rootvg cloning: smitty alt_clone.

Cloning AIX :

• Having online backup. As in case of disk crash.
• When applying new maintenance levels, a copy of the rootvg is made to an alternate disk, then updates are applied to that copy

To view the BOS installation logs : cd /var/adm/ras à cat devinst.log. or alog –o –f bosinstlog. Or smit alog_show

Installation Packages:

Fileset : A fileset is smallest installable unit. Ex: bos.net.uucp

Package : A group of installable filesets Ex: bos.net

Licenced program products : A complete s/w product Ex :BOS

Bundle : A bundle is a list of software that contain filesets, packages and LPPs. Install the software bundle using smitty update_all.

PTF:Program temporary fix. It’s an updated fileset or a new fileset that fixes a previous system problem. PTF’s installed through installp.

APAR: Authorised program analysis report. APAR’s applied to the system through instfix.

Fileset revision level identification : version:release:modification:fixlevel

The file sets that are below level 4.1.2.0, type: oslevel –l 4.1.2.0

The file sets at levels later than the current maintenance level, type: oslevel -g

To list all known recommended maintenance levels on the system, type:oslevel –rq

Oslevel –s for SP level

Current maintenance level: oslevel -r

Installing S/W: Applied and commited

Applied: In applied state the previous version is stored in /usr/lpp/packagename.

Commited : First remove the previous version and go to for the installation

To install filesets within the bos.net software package in /usr/sys/inst.images directory in the applied state: installp –avx –d /usr/sys/inst.images bos.net

Install S/W in commited state: installp –acpX –d/usr/sys/inst.images bos.net

Record of the installp output stored in /var/adm/sw/installp.summary

Commit all updates: installp –cgX all

List all installable S/W : installp –L –d /dev/cd0

Cleaning up after failed installation : installp –C

Removing installed software: installp –ugp

Software Installation: smitty install_latest

Commiting applied updates: smitty install_commit

Rejecting applied updates: smitty install_reject

Removing installed software: smitty install_remove

To find what maintenance level your filesets are currently on : lslpp –l

To list the individual files that are installed with a particular fileset : lslpp –f bos.net

To list the installation and update history of filesets : lslpp –h

To list fixes that are on a CDROM in /dev/cd0 – instfix –T –d /dev/cd0

To determine if APAR is installed or not :     instfix –iK IY737478

To list what maintenance levels installed : instfix –i |grep ML

To install APAR : instfix –K IY75645 –d /dev/cd0

Installing individual fix by APAR: smitty update_by_fix

To install new fixes available from IBM : smitty update_all

Verifying the integrity of OS : lppchk –v

Creating installation images on disk: smitty bffcreate

Verify whether the software installed on your system is in a consistent state: lppchk

To install RPM packages using geninstall. à geninstall –d Media all

Uninstall software: geninstall –u –f file

List installable software on device: geninstall –L –d media.

AIX Boot Process:

1.      When the server is Powered on Power on self test(POST) is run and checks the hardware

2.      On successful completion on POST Boot logical volume is searched by seeing the bootlist

3.      The AIX boot logical contains AIX kernel, rc.boot, reduced ODM & BOOT commands. AIX kernel is loaded in the RAM.

4.      Kernel takes control and creates a RAM file system.

5.      Kernel starts /etc/init from the RAM file system

6.      init runs the rc.boot 1 ( rc.boot phase one) which configures the base devices.

7.      rc.boot1 calls restbase command which copies the ODM files from Boot Logical Volume to RAM file system

8.      rc.boot1 calls cfgmgr –f command to configure the base devices

9.      rc.boot1 calls bootinfo –b command to determine the last boot device

10. Then init starts rc.boot2 which activates rootvg

11. rc.boot2 calls ipl_varyon command to activate rootvg

12. rc.boot2 runs fsck –f /dev/hd4 and mount the partition on / of RAM file system

13. rc.boot2 runs fsck –f /dev/hd2 and mounts /usr file system

14. rc.boot2 runs fsck –f /dev/hd9var and mount /var file system and runs copy core command to copy the core dump if available from /dev/hd6 to /var/adm/ras/vmcore.0 file. And unmounts /var file system

15. rc.boot2 runs swapon /dev/hd6 and activates paging space

16. rc.boot2 runs migratedev and copies the device files from RAM file system to /file system

17. rc.boot2 runs cp /../etc/objrepos/Cu* /etc/objrepos and copies the ODM files from RAM file system to / filesystem

18. rc.boot2 runs mount /dev/hd9var and mounts /var filesystem

19. rc.boot2 copies the boot log messages to alog

20. rc.boot2 removes the RAM file system

21. Kernel starts /etc/init process from / file system

22. The /etc/init points /etc/inittab file and rc.boot3 is started. Rc.boot3 configures rest of the devices

23. rc.boot3 runs fsck –f /dev/hd3 and mount /tmp file system

24. rc.boot3 runs syncvg rootvg &

25. rc.boot3 runs cfgmgr –p2 or cfgmgr –p3 to configure rest of the devices. Cfgmgr –p2 is used when the physical key on MCA architecture is on normal mode and cfgmgr –p3 is used when the physical key on MCA architecture is on service mode.

26. rc.boot3 runs cfgcon command to configure the console

27. rc.boot3 runs savebase command to copy the ODM files from /dev/hd4 to /dev/hd5

28. rc.boot3 starts syncd 60 & errordaemon

29. rc.boot3 turn off LED’s

30. rc.boot3 removes /etc/nologin file

31. rc.boot3 checks the CuDv for chgstatus=3 and displays the missing devices on the console

32. The next line of Inittab is execued

/etc/inittab file format: identifier:runlevel:action:command

MkitabàAdd records to the /etc/inittab file

LsitabàList records in the /etc/inittab file

Chitabàchanges records in the /etc/inittab file

Rmitabàremoves records from the /etc/inittab file

To display a boot list: bootlist –m normal –o

To change a boot list: bootlist –m normal cd0 hdisk0

Troubleshooting on boot process:

Accessing a system that will not boot: Press F5 on a PCI based system to boot from the tape/CDROMàInsert volume 1 of the installation media àselect the maintenance mode for system recoveryà Access a root volume groupàselect the volume groupà

Damaged boot image:Access a system that will not bootàCheck the / and /tmp file system sizeàdetermine the boot disk using lslv –m hd5àRecreate the boot image using bosboot –a –d /dev/hdisknàcheck for CHECKSTOP errors on errlog. If such errors found probably failing hardware. àshutdown and restart the system

Corrupted file system, Corrupted jfs log: Access a system that will not bootàdo fsck on all filw systemsà format the jfs log using /usr/sbin/logform /dev/hd8àRecreate the boot image using bosboot –a –d /dev/hdiskn

Super block corrupted: If fsck indicates that block 8 is corrupted, the super block for the file system is corrupted and needs to be repaired ( dd count=1 bs=4k skip=31 seek=1 if=/dev/hdn of=/dev/hdn)àrebuild jfslog using /usr/sbin/logform /dev/hd8àmount the root and usr file systems by (mount /dev/hd4 /mnt, mount /usr)àCopy the system configuration to backup directory(cp /mnt/etc/objrepos* /mnt/etc/objrepos/backup)àcopy the configuration from the RAM fs(cp /etc/objrepos/Cu* /mnt/etc/objrepos)àunmount all file systemsàsave the clean ODM to the BLV using savebase –d /dev/hdiskàreboot

Corrupted /etc/inittab file: check the empty,missing inittab file. Check problems with /etc/environment, /bin/sh,/bin/bsh,/etc/fsck,/etc/profileàReboot

Runlevelà selected group of processes. 2 is muti user and default runlevel. S,s,M,m for Maintenance mode

Identifying current run levelàcatt /etc/.init.state

Displaying history of previous run levels: /usr/lib/acct/fwtmp < /var/adm/wtmp |grep run-level

Changing system run levels: telinit M

Run level scripts allow users to start and stop selected applications while changing the run level. Scripts beginning with k are stop scripts and S for start scripts.

Go to maintenance mode by using shutdown -m

Rc.boot fle: The /sbin/rc.boot file is a shell script that is called by the init. rc.boot file configures devices, booting from disk, varying on a root volume group, enabling fle systems, calling the BOS installation programs.

/etc/rc file: It performs normal startup initialization. It varyon all vgs, Activate all paging spaces(swapon –a), configure all dump devices(sysdumpdev –q), perform file system checks(fsck –fp), mount all

/etc/rc.net: It contains network configuration information.

/etc/rc.tcpip: it start all network related daemons(inted, gated, routed, timed, rwhod)

Backups:

MKSYSB : Creates a bootable image of all mounted filesystems on the rootvg. This command is for restore a system to its original state.

Tape Format : BOS boot image(kernel device drivers), BOS install image(tapeblksz, image.data, bosinst.data), dummy table of contents, rootvg backup

Exclude file systems using mksysb –ie /dev/rmt0

Cat /etc/exclude.rootvg

List content of MKSYSB image smitty lsmksysb

Restore a mksysb image : smitty restmksysb

Savevg command finds and backs up all files belonging to the specified volume group. Ex: savevg –ivf /dev/rmt0 uservg.

Restvg command restores the user volume group

Backup command backs up all files and file systems. Restore command extracts files from archives created with the backup command.

Verify the content of a backup media à tcopy /dev/rmt0

Daily Management :

/etc/security/environ : Contains the environment attributes for a user.

/etc/security/lastlog : Its an ascii file that contains last login attributes.(time last unsuccessful login, unsuccessful login

count, time last login)

/etc/security/limits : It specify the process resource limits for each user

/etc/security/user :

/usr/lib/security/mkuser.default : It contains the default attributes for a new user.

/etc/utmp file contains record of users logged into the system Command : who –a

/var/adm/wtmp file contains connect-time accounting records

/etc/security/failedlogin contains record of unsuccessful login attempts.

/etc/environment contains variables specifying the basic environment for all processes.

/etc/profile file is first file that the OS uses at login time.

To enable user smith to access this system remotely : chuser rlogin=true smith

Remove the user rmuser smith

Remove the user with remove the authentication information rmuser –p smith

Display the current run level : who –r

How to display the active processes : who –p

Changing the current shell : chsh

Change the prompt : export PS1=”Ready.”

To list all the 64-bit processes : ps –M

To change the priority of a process : nice and renice

SUID –set user id – This attribute sets the effective and saved user ids of the process to the owner id of the file on execution

SGID – set group id -- This attribute sets the effective and saved group ids of the process to the group id of the file on execution

CRON daemon runs shell commands at specified dates and times.

AT command to submit commands that are to be run only once.

System Planning:

RAID: Redundant array of independent disks.

RAID 0: Striping. Data is split into blocks of equal size and stored on different disks.

RAID 1: Mirroring. Duplicate copies are kept on separate physical disks.

RAID 5: Striping with Parity. Data is split into blocks of equal size. Additional data block containing parity information.

RAID 10: It is a combination of mirroring and striping.

AIX 5.3 requires at least 2.2 GB of physical space.

Configuration:

ODM: ODM is a repository in which the OS keeps information about your system, such as devices, software, TCP/IP configuration.

Basic Components of ODM: object classes, objects, descriptors

ODM directories: /usr/lib/objrepos, /usr/share/lib/objrepos, /etc/objrepos

Following steps for NFS implementation:

<!--[if !supportLists]-->· <!--[endif]-->NFS daemons should be running on both server and client

<!--[if !supportLists]-->· <!--[endif]-->The file systems that need to be remotely available will have to be exported(smitty mknfsexp, exportfs –a , showmount –e myserver)

<!--[if !supportLists]-->· <!--[endif]-->The exported file system need to be mounted on the remote systems

NFS services: /usr/sbin/rpc.mountd, /usr/sbin/nfsd, /usr/sbin/biod,rpc.statd, rpc.lockd

Changing an exported file system: smitty chnfsexp TCP/IP Daemons: inetd,gated, routed,named,

Configuration:

ODM: ODM(Object data manager) is a repository in which the OS keeps information regarding your system, such as devices, software or TCP/IP information.

ODM information is stored in /usr/lib/objrepos, /usr/share/lib/objrepos, /etc/objrepos.

ODM commands: odmadd, odmchange, odmcreate, odmshow, odmdelete, odmdrop, odmget,

To start the graphical mode smit using smit –m

Creating alias: alias rm=/usr/sbin/linux/rm

Export PATH=/usr/linux/bin:$path; print $path

Netwok File System:

Daemons: Server side(/usr/sbin/rpc.mountd, /usr/sbin/nfsd, portmap, rpc.statd, rpc.lockd) Client side ( /usr/sbin/biod)

Start the NFS faemons using mknfs –N. To start all nfs daemons using startsrc –g nfs.

Exporting nfs directories:

• Verify nfs is running or not using lssrc –g nfs
• Smitty mknfsexp
• Specify path name, set the mode(rw,ro). It updates /etc/exports file.
• /usr/sbin/exportfs –a à it sends all information in the /etc/exports to kernel.
• Verify all file systems exported or not using showmount –e Myserver

Exporting an nfs directory temporarily using exportfs –i /dirname

Un exporting an nfs directory using smitty rmnfsexp

Establishing NFS mounts using smitty mknfsmnt

Changing an exported file system using smitty chnfsexp

Network configuration:

Stopping TCP IP daemons using /etc/tcp.clean script.

/etc/services file contains information about the known services

Add network routes using smitty mkroute or route add –net 192.168.1 –netmask 255.255.255.0

Traceroute command shows the route taken

Changing IP address smitty mktcpip

Identifying network interfaces : lsdev –Cc if

Activating network interface: ifconfig interface address netmask up

Deactivating network interface: ifconfig tr0 down

Deleting an address: ifconfig tr0 delete

Detaching network interface: ifconfig tr0 detach

Creating an IP alias: ifconfig interface address netmask alias

To determine MTU size of a network interface using lsattr –El interface.

Paging Space: A page is unit of virtual memory that holds 4kb of data.

Increasing paging space: chps –s 3 hd6 ( it’s a 3LP)

Reducing paging space: chps –d 1 hd6

Moving a paging space within the VG: migratepv –l hd6 hdisk0 hdisk1

Removing a paging space: swapoff /dev/paging03; rmps paging03

Device configuration:

Lscfgà detail about devices ex: lscfg –vpl rmt0

To show more about a particular processor: lsattr –El proc0

To discover how much memory is installed: lsattr –El sys0 | grep realmem.

To show processor details: lscfg |grep proc or lsdev –Cc processor

To show available processors: bindprocessor –q

To turn on SMT using smtctl –m on –w boot

To turn off SMT : smtctl –m off –w now

Modifying an existing device configuration using chdev. The device can be in defined,stopped,available state.

To change maxuproc value: chdev –l sys0 –a maxuproc=100

Remove a device configuration: rmdev –Rdl rmt0

Bootinfo –y command à returns 32 bit or 64 bit.

Commands to run enable 64 bit: ln –sf /usr/lib/boot/unix_64 /unixàln –sf /usr/lib/boot/unix_64 /usr/lib/boot/unixàbosboot –ad /dev/ipldevice àshutdown –r àls –al /unix

File Systems:

Types: Journaled, Enhanced journaled, CDROM, NFS

FS Structure: Super block, allocation groups, inodes, blocks, fragments, and device logs

Super block: It contains control information about file system, such as overall file system in 512 byte blocks, FS name, FS log device, version no, no. of inodes, list of free inodes, list of free data blocks, date and time of creation, FS state.

This data is stored in first block of FS and 31.

Allocation group:It consists of inodes and corresponding data blocks.

Inodes: It contains control information about the file. Such as type, size, owner, date and time when the file was created, modifies, last accessed, it contains pointers to data blocks that stores actual data. For JFS maximum no.of inodes and files is determined by the no. of bytes per inode(NBPI). For JFS 16MB inode. For JFS2 there is no NBPI.

Data Blocks: actual data. The default value is 4KB.

Device logs: JFS log stores transactional information. This data can be used to roll back incomplete operations if the machine crashes. Rootvg use LV hd8 as a common log.

FS differences:

Function JFS JFS2

Max FS Size 1TB 4PB

Max File Size 64G 4PB

Np.of inodes Fixed Dynamic

iNode size 128B 512B

Fragment Size 512 512

Block size 4KB 4KB

Creatinf FS: crfs –v jfs2 –g testvg –a size=10M –m /fs1

Display mounted FS: mount

Display characteristics of FS: lsfs

Initialize log device: logform /dev/loglv01

Display information about inodes: istat /etc/passwd

Monitoring and Performance Tuning:

Quotaon command enables disk quotas for one or more file systems

Ouotaoff command disables disk quotas for one or more file systems

Enable user quotas on /home: chfs –a “quota=userquota,groupquota” /home

To check the consistency of the quota files using quotacheck

Edquota command to create each user or group’s soft and hard limits for allowable disk space and maximum number of files

Error logging is automatically started by the rc.boot script

Errstop command stops the error logging

The daemon for errlog is errdemon

The path to your system’s error log file: /usr/lib/errdemon –l

Change the maximum size of the error log: errdemon –s 2000000

Display all the errors which have an specific error id: errpt –j 8527F6F4

Display all the errors logged in a specific time: errpt –s 1122164405 –e 1123100405

To delete all the entries: errclear 0

Delete all the entries classified as software errors: errclear –d s 0

VMSTAT: It reports kernel threads, virtual memory, disks, traps and cpu activity.

To display 5 summaries at 1 second intervals use vmstat 1 5

Kthr(kernel thread state) ràaverage number of runnable kernel threads. Bàaverage number of kernel threads placed in the VMM wait queue

Memory(usage of virtual and real memory). Avm à active virtual pages, total number of pages allocated in page space. A high value is not an indicator of poor performance. Freàsize of the free list. A large portion of real memory is utilized as a cache for file system data.

Page(information about page faults and page activity). Reàpager input/output list, piàpages paged in from paging space, poàpages paged out to paging space, fràpages freed, sràpages scanned by page replacement algorithm, cyà clock cycles used by page replacement algorithm

Faults(trap and interrupt rate averages per second): inàdevice interrupts, syàsystem calls, csàkernel thread context switches

CPU(breakdown of percentage usage of CPU time): usàuser time, syàsystem time, idàcpu idle time,waàwaiting for request, pcànumber of physical processors consumed ecàthe percentage of entitled capacity consumed.

Disks(provides number of transfers per second)

SAR: sar 2 5(%usr, %sys, %wio, %idle, physc)

To report activity for the first 2 processors for each second for next 5 times: sar –u –P 0,1 1 5

Topas:

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Tuning Parameters:

/etc/tunables directory centralizes the tunable files.

Nextboot: this file is automatically applied at boot time.

Lastboot: It contains tunable parameters with their values after the last boot.

Lastboot.log: It contains logging of the creation of the lastboot file.