High availability is sometimes confused with simple hardware availability. Fault tolerant,redundant systems (such as RAID) and dynamic switching technologies (such as DLPAR)provide recovery of certain hardware failures, but do not provide the full scope of error detection and recovery required to keep a complex application highly available.
A modern, complex application requires access to all of these components:
• Nodes (CPU, memory)
• Network interfaces (including external devices in the network topology)
• Disk or storage devices.
Recent surveys of the causes of downtime show that actual hardware failures account for only
a small percentage of unplanned outages. Other contributing factors include:
• Operator errors
• Environmental problems
• Application and operating system errors.
Reliable and recoverable hardware simply cannot protect against failures of all these different
aspects of the configuration. Keeping these varied elements—and therefore the application—highly available requires:
• Thorough and complete planning of the physical and logical procedures for access and operation of the resources on which the application depends. These procedures help to avoid failures in the first place.
• A monitoring and recovery package that automates the detection and recovery from errors.
• A well-controlled process for maintaining the hardware and software aspects of the cluster configuration while keeping the application available.
Monday, April 27, 2009
High Availability Cluster Multi-Processing for AIX
The IBM HACMP software provides a low-cost commercial computing environment that ensures quick recovery of mission-critical applications from hardware and software failures.
HACMP has two major components: high availability (HA) and cluster multi-processing
(CMP).
With HACMP software, critical resources remain available. For example, an HACMP cluster could run a database server program that services client applications. The clients send queries to the server program that responds to their requests by accessing a database, stored on a shared
external disk.
This high availability system combines custom software with industry-standard hardware to minimize downtime by quickly restoring services when a system, component, or application fails. Although not instantaneous, the restoration of service is rapid, usually within 30 to 300 seconds.
In an HACMP cluster, to ensure the availability of these applications, the applications are put under HACMP control. HACMP takes measures to ensure that the applications remain available to client processes even if a component in a cluster fails. To ensure availability, in case of a component failure, HACMP moves the application (along with resources that ensure access to the application) to another node in the cluster.
HACMP has two major components: high availability (HA) and cluster multi-processing
(CMP).
With HACMP software, critical resources remain available. For example, an HACMP cluster could run a database server program that services client applications. The clients send queries to the server program that responds to their requests by accessing a database, stored on a shared
external disk.
This high availability system combines custom software with industry-standard hardware to minimize downtime by quickly restoring services when a system, component, or application fails. Although not instantaneous, the restoration of service is rapid, usually within 30 to 300 seconds.
In an HACMP cluster, to ensure the availability of these applications, the applications are put under HACMP control. HACMP takes measures to ensure that the applications remain available to client processes even if a component in a cluster fails. To ensure availability, in case of a component failure, HACMP moves the application (along with resources that ensure access to the application) to another node in the cluster.
Sunday, April 26, 2009
IBM AIX Operating System an Overview
Click the following link for information on: IBM AIX Operating System an Overview
IBM AIX Version 6.1 Differences Guide
Click the following link for more information on: IBM AIX Version 6.1 Differences Guide
AIX - LVM - List File System
IBM - AIX - List File System
We can list file system details using lsfs command
#lsfs – List all filesystems in the /etc/filesystems entry
#lsfs –q (List all filesystems with detailed info)
#lsfs –a (list all filesystems (default)
#lsfs –l (specify the output in the list format)
#lsfs –c (specify the output in the column format)
#lsfs –v jfs (List all jfs filesystems)
We can list file system details using lsfs command
#lsfs – List all filesystems in the /etc/filesystems entry
#lsfs –q (List all filesystems with detailed info)
#lsfs –a (list all filesystems (default)
#lsfs –l (specify the output in the list format)
#lsfs –c (specify the output in the column format)
#lsfs –v jfs (List all jfs filesystems)
AIX - LVM - Change File System
AIX - LVM - Change File System
Using chfs command we can rename and increase the size of the file system online
We want to increase file system size
#chfs –a size=+block size /filesystem name
#chfs –a size=+32m /filesystem name
#chfs-a size=+4g /filesystem name
+block size – We can mention the size using blocks (2048 blocks = 1MB)
+32m – We can mention the size using MB
+4g – We can mention the size using GB
After increasing the file system size, we can verify using commands
#df –k
#ls –q /newfs
Rename the file system using chfs command
#lsfs /newfs
It will display /newfs details
#
Now we want to rename /newfs to /testfs then your command will be
#chfs –m /testfs /newfs
After executing the above command /newfs renamed as /testfs
We can auto mount the file system while booting using chfs command
#chfs –A /testfs
Using chfs command we can rename and increase the size of the file system online
We want to increase file system size
#chfs –a size=+block size /filesystem name
#chfs –a size=+32m /filesystem name
#chfs-a size=+4g /filesystem name
+block size – We can mention the size using blocks (2048 blocks = 1MB)
+32m – We can mention the size using MB
+4g – We can mention the size using GB
After increasing the file system size, we can verify using commands
#df –k
#ls –q /newfs
Rename the file system using chfs command
#lsfs /newfs
It will display /newfs details
#
Now we want to rename /newfs to /testfs then your command will be
#chfs –m /testfs /newfs
After executing the above command /newfs renamed as /testfs
We can auto mount the file system while booting using chfs command
#chfs –A /testfs
AIX - LVM - Create File System
AIX - LVM - Create File System
Create FS
Using crfs command we can create a file system. File systems belongs to LV’s
Whenever we create the file system we should mention the LV name
#crfs –v jfs2 –d testlv –m /newfs (Normal creation)
The /newfs file system created on testlv.
#crfs –v jfs2 –g testvg –a size=64465 –m /newfs (Directly we can create /fs from VG
This case lv name will be lv00 or lv01 like this after that also we can rename the lv name)
Create FS
Using crfs command we can create a file system. File systems belongs to LV’s
Whenever we create the file system we should mention the LV name
#crfs –v jfs2 –d testlv –m /newfs (Normal creation)
The /newfs file system created on testlv.
#crfs –v jfs2 –g testvg –a size=64465 –m /newfs (Directly we can create /fs from VG
This case lv name will be lv00 or lv01 like this after that also we can rename the lv name)
AIX - LVM - Remove Logical Volume
AIX - LVM - Remove Logical Volume
If we want to LV testlv from server
#rmlv testlv (If data is available in testlv It will ask confirmation)
#rmlv –f testlv (It won’t ask any confirmation, directly it will delete the data)
After executing the above command testlv removed from the server.
If we want to LV testlv from server
#rmlv testlv (If data is available in testlv It will ask confirmation)
#rmlv –f testlv (It won’t ask any confirmation, directly it will delete the data)
After executing the above command testlv removed from the server.
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