UNIX for Dummies Questions & Answers

I have no idea what I should set the topic here =='
This is my story, please you there kindly help me I'm quite newbie for this.

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My host server is CentOS, I spared 9.9GB for /var path that used by MySQL
and...It's full because of heavy load traffic, then I couldn't access the database anymore.

I solved this problem by moving my database out to another directory that have more space such as /usr/ and create a symbolic link. After that, I can access my database again so, I deleted some data and wanna move it back but... I check sizing with du -sh and nothing change. It's still 6.3 GB even it's shown 3.2GB in phpMyAdmin page.

Is there something wrong? or I did anything incorrect?
Please suggest to me

Thank you in advance

First: you should put your database not in "/usr" - never! "/var" is only slightly better, but still not right. Create a directory "/opt", then create a filesystem "/opt/mydatabase" (or whatever - name is up to you), mount this filesystem and put your database there. The reason is that every directory in UNIX has its fixed contents and "/usr" is for the operation system. Search for "file system hierarchy standard" on the net and you will find a document explaining all this in detail. FHS is not a standard, but a very good guideline.

Second: a database is a collection of files, managed by some software. The files (what the OS reports as size) are of fixed size and are preallocated (mostly for reasons of speed). If this preallocated space is filled with something or not does not make any difference for the OS. PhpMyAdmin is a tool which queries the database software and this will tell you how much content is really stored within this space. But if you delete (or add) content this will change nothing for the size of the preallocated files the database uses. This is why the OS and PhpMyAdmin report different sizes for the database. To reduce the space the OS sees you need to shrink the "tablespaces" (i hope it is called this in MySQL too - this is the name in Oracle) to release some of the preallocated space.

I hope this helps.

bakunin