Common Connect - August 2009

If;the;root;disks;are;imaged;from;original media;or;a;NIM;installation,;you;will;need to;set;up;and;configure;all;the;devices when;the;server;boots;up;(except;for;the network;adapter;that;NIM;uses).;This;is;the most;time-intensive;course;of;action;for configuring;devices;and;will;require;the most;attention.;And;if;you;used;NIM,;you may;need;to;change;the;IP;address;and/or hostname;when;the;cutover;time;occurs.

If;the;root;disks;will;be;physically;moved to;the;new;LPAR;or;if;you;select;the;option in;NIM;to;recreate;devices,;you;will;need;to sort;out;a;number;of;old;and;new;devices. For;example,;if;the;original;server;had;one Ethernet;adapter;(ent0);and;the;new;server has;one;Ethernet;adapter;(ent1),;the;new server;will;have;one;defined;adapter;(ent0), one;available;adapter;(ent1),;and;no;active interface;with;a;working;IP;address.;So,;you will;have;to;delete;both;interfaces;using the;rmdev –dl <interface> -R;command,;re-detect;the;correct;device;using;cfgmgr,;and then;set;an;IP;address.;The;same;process applies;to;any;other;adapters;and;disks;that were;formerly;defined.

I;have;also;found;that;the;one;thing;that tends;to;come;back;and;haunt;me;is;device definitions;that;do;not;correlate;directly;to a;physical;piece;of;hardware—in;particular, asynchronous;I/O;devices;(AIO);on;database servers.;For;these;devices,;first;run;a;mkdev operation;to;make;the;device;available, then;run;chdev;to;set;the;device;to;be available;upon;reboot.;Otherwise,;there;will be;some;very;agitated;DBAs;once;the;new LPAR;is;active.

Conclusion

In;my;years;of;experience,;I;have;performed dozens;of;successful;LPAR;migrations.;And the;one;piece;of;advice;I;cannot;reiterate enough;is;this:;Plan,;plan,;and;plan;some more!;Although;it;may;seem;like;gathering so;much;information;about;the;original server;is;trivial;and;going;over;each;and every;part;of;the;hardware;a;waste;of;time, I;cannot;count;the;number;of;times;where knowing;something;abstract;like;a;PVID, Maximum;Transmission;Unit;(MTU);size, or;timeout;value;came;in;handy;to;save;a customer;account.;There;is;no;worse;feeling than;flipping;the;switch;and;watching;a new;LPAR;grind;to;a;halt,;but;by;avoiding these;common;gotchas,;you;will;have;the greatest;chance;for;success;in;your;LPAR migration.

About the author

Christian Pruett is a senior UNIX systems administrator with more than 14 years of experience with AIX, Sun Solaris, Linux, and HP/UX in a wide variety of industries, including computing, agriculture, and telecommunications. He is the co-author of two IBM Redbooks on AIX, has served as a UNIX book review for O’Reilly Publishing, and has worked on several of the IBM AIX certification exams. He resides in Colorado with his wife and two children. You can reach Christian at pruettc@gmail.com.

Resources

Learn

UNIX on Power systems:;Learn;more;about;AIX;Power;systems;software.

http://www-03.ibm.com/systems/power/software/aix/index.html

HMC attached system setup:;Learn;how;to;set;up;your;system;using;the;Hardware

Management;Console.

http://www.ibm.com/developerworks/wikis/display/WikiPtype/HMC+attached+System+

Setup

AIX wiki:;Get;the;technical;information;you;need;from;this;collaborative;site.

http://www.ibm.com/developerworks/wikis/display/WikiPtype/Home

AIX and UNIX:;Visit;the;developer Works;AIX;and;UNIX;zone;provides;a;wealth;of information;relating;to;all;aspects;of;AIX;systems;administration;and;expanding;your