AIX (Advanced Interactive eXecutive) is a series of proprietary Unix operating systems developed and sold by IBM.
Performance Optimization With Enhanced RISC (POWER) version 7 enables a unique performance advantage for AIX OS.
POWER7 features new capabilities using multiple cores and multiple CPU threads, creating a pool of virtual CPUs.
AIX 7 includes a new built-in clustering capability called Cluster Aware
AIX POWER7 systems include the Active Memory Expansion feature.

Tuesday, December 25, 2012

DIFFERENCES BETWEEN JFS AND ENHANCED JFS



WHAT IS MEANT BY JOURNAL  LOG (JFSLOG)


Journaled File Systems LOG is used to stores transactional information about file system metadata changes and can be used to roll back incomplete operations if the machine crashes  That's why log devices should always be protected by mirroring or raid 0+1 or raid 5


You cannot see files associate with jfslog devices because they're not mounted over any File Systems  They're raw devices used by Logical Volumen Manager (LVM) to keep information about changes in metadata  You can create a jfslog device and format it (destructive operation) and assign to any JFS, even more, you can assign the same jfslog more than one JFS  You can create a jfslog type 2 to log metadata for JFS2 File Systems or use the new INLINE log device for JFS2 only



DIFFERENCES BETWEEN JFS AND ENHANCED JFS


There are many differences between JFS and Enhanced JFS.


Table 1. Functional Differences between JFS and Enhanced JFS


Function                                                   JFS                                              Enhanced JFS


Optimization                                        32-bit kernel                                     64-bit kernel


Maximum file system size                  32 terabyte                                        4 petabytes


Note: This is an architectural limit. AIX® currently only supports up to 16 terabytes.


Maximum file size                              64 gigabytes                                       4 petabytes


Note: This is an architectural limit. AIX currently only supports up to 16 terabytes.


Number of I-nodes                        Fixed at file system creation       Dynamic, limited by disk space


Large file support                             As mount option                                 Default


Online defragmentation                            Yes                                                 Yes


namefs                                                       Yes                                                Yes


DMAPI                                                    No                                                  Yes


Compression     Yes         No


Quotas                 Yes         Yes


Deferred update              Yes         No


Direct I/O support           Yes         Yes


Note:


•             Cloning with a system backup with mksysb from a 64-bit enabled JFS2 system to a 32-bit system will not be successful.


•             Unlike the JFS file system, the JFS2 file system will not allow the link() API to be used on its binary type directory. This limitation may cause some applications that operate correctly on a JFS file system to fail on a JFS2 file system.


•             Journaling


Before writing actual data, a journaling file system logs the metadata, thus incurring an overhead penalty that slows write throughput.


•             Directory organization


An index node, or i-node, is a data structure that stores all file and directory properties. When a program looks up a file, it searches for the appropriate i-node by looking up a file name in a directory.


•             Scaling


The main advantage of using Enhanced JFS over JFS is scaling.
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