written by: Finn Orfano•edited by: Michael Dougherty•updated: 6/7/2010
Maintenance measures should not be taken for granted; rather we need to understand the purpose behind every measure and the situation in which that measure should be taken.
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Mac Maintenance Myths
Here are some maintenance myths that are prevalent among many Mac users.
Myth 1: Defrag your hard disk
Generally if the files are large in size and there is not any free contiguous blank space on the hard disk in order to accommodate that file, that file is divided into many chunks to place itself on the drive. Division of a file into many chunks and storage in separate locations is called Fragmentation. A bit of fragmentation is fine but more of it requires longer time to search these on the disk for read and write operations. So in order to prevent the fragmentation, there is a process called Defragmentation. It arranges the file chunks in such a way that they are placed contiguously on the hard disk again. Although defragmentation improves speed of the system but it is not required with Mac OS X 10.2 and later. It is because Mac OS X has a delayed allocation feature for Extended-formatted volumes. This enables combining of a number of data chunks into a single large chunk. Also, the modern day hard drives are fast enough for the users to not notice result of fragmentation. Therefore, there isn’t really much need to defrag your hard disk.
Myth 2: Repair the permissions
Mac OS X’s permissions are used to assign users a certain level of access to all the items on the hard disk. Sometimes, thepermissions on files become corrupted or changed incorrectly, which cause problems. It is commonly suggested that Disk Utility’s Repair feature is used to repair these permissions. The reality is that the Disk Utility’s Repair feature works only with a particular set of OS X systems files. The repairing process does not affect applications, user files or third-party files at all. This means that repairing the system files with corrupted permissions will unlikely prevent problems caused by non-system objects from occurring again.
Myth 3: Update prebinding
In the previous version of Mac OS, it was possible to speed up launching of programs by updating the prebinding information that was stored by the operating system. But the newer versions of Mac OS X don’t require it to speed up running of the processes.
Page 2: Myth four and myth 5
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Mac keeps some data in cache for quicker access to it, therefore cleaning the cache regularly will slightly slowdown your Mac’s performance.
Mac runs a number of UNIX maintenance scripts but if these scripts didn’t run because your computer was switched off, this will adversely affect your Mac.
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Mac Maintenance Myths - Page 2
Myth 4: Regularly Run Unix Maintenance Scripts
Mac OS has a set of UNIX scripts, which are supposed to delete previous/ old log files or temporary files and rebuilding Unix’s locate and whatis database. By default, these UNIX scripts are programmed to run on daily, weekly and monthly basis and it is often emphasized that these scripts should be run regularly. The reality is that frequently running these scripts is not helpful because the old log files help Mac OS X in easy and quicker access of data.
It is correct that if your Mac is switched off, the scripts do not run. If you have decided to let these scripts run as these are scheduled and these do not one day because your Mac was switched off, the situation won’t become worse as you might think. It is because a couple of missed executions will not have a bad affect on your Mac.
Myth 5: Clean the caches
Frequently accessed data is stored in a nearly located small memory called Cache. The operating system itself and some applications store frequently accessed files in the cache. Whenever the application requires a file, it first searches for it in the cache and if it is not found in that, it looks for it in the hard disk. In most cases, the file is found in the cache and this hugely reduces the access time, which results in increased processing speed.
However, it is often recommended that the cache data should be deleted on a regular basis but doing this actually add additional work to the operating system. If these files are deleted, the system will need to search for the file in more distant location (hard disk), whose speed is also slower than cache (RAM) and it would require more time to fetch it from there. The system will also need to recreate copies of these files and place them in the cache again and again. This would be more of a liability than gaining advantage from the cache.