AIX 5L Problem Determination - IBM Redbooks

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4. Initiate an iptrace (client, server, or network), reproduce the problem, then view the ipreport output to determine where the problem is. 8.4.2 NFS mount problems Mount problems fall into one of the following categories: ► File system not exported, or not exported to a specific client. Correct server export list (/etc/exports) ► Name resolution different from the name in the export list. Normally, it is due to one of the following causes: – The export list uses a fully qualified name but the client host name is resolved without a network domain. Fully qualified names cannot be resolved. Mount permission is denied. Usually, this happens after upgrade activity and can be fixed by exporting to both forms of the name. – The client has two adapters using two different names and the export only specifies one. This problem can be fixed by exporting both names. – The server cannot do a lookuphostbyname or lookuphostbyaddr onto the client. To check, make sure the following commands both resolve to the same system: host name host ip_addr ► The file system mounted on the server after exportfs was run. In this case, the exportfs command is exporting the mount point and not the mounted file system. To correct this problem run: /usr/etc/exportfs -ua; /usr/etc/exportfs -a Then fix the /etc/filesystems file to mount the file system on boot, so it is already mounted when NFS starts from /etc/rc.nfs at system startup. ► Changes in the exports list, mounts, or somewhere else unexpectedly can sometimes lead to mountd getting confused. This usually happens following mounting, exporting, or because of mount point conflicts and similar errors. To correct this condition, mountd needs to be restarted by using the following commands: # stopsrc -s rpc.mountd # startsrc -s rpc.mountd ► The system date being extremely off on one or both machines is another source of mount problems. To fix this, it is necessary to set the correct date and time, then reboot the system. 190 IBM ^ Certification Study Guide - AIX 5L Problem Determination Tools and Techniques
► Slow mounts from AIX Version 4.2.1 or later, clients running NFS Version 3 to AIX Version 4.1.5 or earlier and other non-AIX servers running NFS Version 2. NFS Version 3 uses TCP by default, while NFS Version 2 uses UDP only. This means that the initial client mount request using TCP will fail. To provide backwards compatibility, the mount is retried using UDP, but this only occurs after a timeout. To avoid this problem, NFS Version 3 provides the proto and vers parameters with the mount command. These parameters are used with the -o option to hard wire the protocol and version for a specific mount. The following example forces the use of UDP and NFS Version 2 for the mount request: # mount -o proto=udp,vers=2,soft,retry=1 platypus:/test /mnt ► Older non-AIX clients can also incur mount problems. If your environment has such clients, you need to start mountd with the -n option: # stopsrc -s rpc.mountd # startsrc -s rpc.mountd -n ► Another mount problem that can occur with older non-AIX clients is when a user who requests a mount is in more than eight groups. The only work-around for this is to decrease the number of groups the user is in or mount using a different user. 8.4.3 Increasing NFS Socket Buffer Size You may find that the netstat -s command indicates a significant number of UDP socket buffer overflows. As with ordinary UDP tuning, increase the sb_max value. You also need to increase the value of nfs_socketsize, which specifies the size of the NFS socket buffer. The following is an example: # no -o sb_max=131072 # nfso -o nfs_socketsize=130972 Note: In AIX Version 4, the socket size is set dynamically. Configurations using the no and nfso commands must be repeated every time the machine is booted. Add them in the /etc/rc.net or /etc/rc.nfs file immediately before the nfsd daemons are started and after the biod daemons are started. The position is crucial. 8.4.4 The biod and nfsd daemons Starting with AIX 4.2.1, there is a single nfsd daemon and a single biod daemon, each of which is multi-threaded (multiple kernel threads within the process). Also, the number of threads is self-tuning in that it creates additional threads as needed. You can, however, tune the maximum number of nfsd threads by using Chapter 8. Network problem determination 191
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ibm.com/redbooks IBM Certification
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Note: Before using this information
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3.5.1 The /etc/inittab file . . . .
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7.2.1 Data relocation . . . . . . .
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9.9.1 The lslicense command . . . .
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x IBM ^ Certification Study Guide -
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10-12 Performance tuning flowchart
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8-7 Commonly used flags of the rout
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Trademarks The following terms are
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This publication does not replace p
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Comments welcome Your comments are
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1.1 Certification requirements To a
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e. Verify that file systems are mou
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Preparation for this exam is the to
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2.1 Defining the problem The first
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If the problem occurs on more than
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2.4.1 Answers The following are the
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3.1 A general overview of the boot
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mainly to components on the motherb
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Figure 3-3 Task selection menu in d
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3.2.2 PCI systems next step is to s
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3.3 Boot phase 1 Newer PCI architec
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3.4 Boot phase 2 In boot phase 2, t
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As mentioned, there are a lot of di
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3.4.3 LED 518 product documentation
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Figure 3-9 Boot phase 3 /etc/initta
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3.5.2 LED 553 3.5.3 LED c31 3.5.4 L
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3.5.5 pSeries servers A specific LE
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When the system is gracefully shut
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LED Reason/action c31 Define the co
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3. A file system is being mounted b
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3.9.1 Answers 3.10 Exercises The fo
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4.1 Hardware basics RS/6000 and pSe
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The most important fields in the pr
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Figure 4-1 Main diagnostics menu Th
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► Full testing requires that the
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3. Place the CD-ROM into the drive.
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Note: This service aid is only pres
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2. Select Change Show use of an SSA
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LED 299 A LED code of 299 shows tha
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Figure 4-2 Format of the 103 code m
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4.5 Quiz The following assessment q
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4.5.1 Answers 4.6 Exercises The fol
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5.1 Configuring the dump device Pri
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5.2 Starting a system dump A user-i
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A command status screen will be dis
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If the system does not have a key s
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The shconf command is invoked when
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5.4 Increasing the size of the dump
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Setting output device to /dev/rmt0.
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Look at the time of the dump and th
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Failure Causes SOFTWARE PROGRAM Rec
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Using crash, you can examine: ► A
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► ? or help[] Lists all subcomman
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LR: .waitproc+d4 (0000edc4) 2ff3b38
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DSIRR Data Storage Interrupt Reason
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*prevthread:0xe6000000 *nextthread:
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In this example, the VMM return cod
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The snap command syntax is as follo
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Flag Description -t Format Lists ea
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Flag Description -p Device Temporar
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Figure 5-3 Error log case study 2.
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Figure 5-4 Case study Which of the
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5.10.1 Answers 5.11 Exercises The f
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6.1 The error daemon The error logg
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To change the current log file, the
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To process a report from the error
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Flag Description -g Displays the AS
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Flag Description -F FlagList Select
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Probable Causes ERRDEMON STARTED AU
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To display a detailed report of all
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USER ID 0 0=SOFT IPL 1=HALT 2=TIME
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Resource Class: planar Resource Typ
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Flag Description -k ErrorID[,ErrorI
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6.5.1 Setting up an accounting syst
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6.6 The syslogd daemon The syslogd
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Use the following message priority
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3. A system operator accidentally d
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6.7.1 Answers 6.8 Exercises The fol
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7.1 LVM data The Logical Volume Man
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later). The method used in AIX Vers
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second. Large values indicate a CPU
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kernel routine records the process
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syncd 1 2 2 0 0 0 sh 1 1 1 0 0 0 sl
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The memory columns The memory colum
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The sr column The sr column shows t
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If you want to sort to the sixth co
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► Workload Management Class (-W)
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schedtune limitations The schedtune
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schedtune parameters are reset by t
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Normal files are automatically mapp
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tty: tin tout avg-cpu: % user % sys
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When looking for performance proble
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those that do not. If you are runni
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The netstat -m command The netstat
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spec buf 1 0 0 0 128 128 0 locking
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Late Collision Errors The Late Coll
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The retrans column displays the num
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Figure 10-3 Web-based System Manage
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Superclasses A superclass is a clas
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► Shared subclass: This subclass
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The sequence of attributes within a
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This manual assignment can be done
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This defines three levels of privil
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The class assignment is done by WLM
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Figure 10-8 shows the SMIT panel wh
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Figure 10-10 SMIT panel for rset re
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10.6.1 The dbx command The dbx comm
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Subcommand Description return Conti
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15) phxent_dd [5 entries] 16) kbddd
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10.8 Command summary The following
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10.8.4 The nfsstat command 10.9 Qui
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6. Which command will show system c
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11.1 Overview 11.1.1 Terminology 11
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Note: Before installing a new set o
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► APAR number, such as IY00301. I
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► To install all filesets associa
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Table 11-2 Commonly used flags of t
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11.5 Quiz Flag Description -f Check
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- A Web server The browser must be
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Figure 12-2 HTTP filesets If you ar
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- Remote computer Type the remote d
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Figure 12-4 Documentation Library S
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CISPR International Special Committ
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I/O Input/Output I 2 C Inter Integr
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OEM Original Equipment Manufacturer
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SPM System Performance Measurement
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Other resources These publications
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phase1 figure 23 phase2 15, 24, 36
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pc.statd 189 daemons shdaemon 73 te
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host name resolution telnet login p
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N name resolution diagnostic 185 pr
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ecent CPU usage 241 recovering an i
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System Resource Controller (SRC) 13
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IBM Certification Study Guide - AIX
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AIX 5L Problem Determination - IBM Redbooks

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