Oracle FAQ | Your Portal to the Oracle Knowledge Grid |
Home -> Community -> Mailing Lists -> Oracle-L -> Re: Defragmenting a RAID 5 volume?
On 01/21/2004 03:04:26 AM, Rhojel_Echano_at_sgs.com wrote:
> GB. My question is, can a RAID 5 volume be defragmented? Is it sane,
> technically? The volume is 130GB in size...
You are defragmenting a file system, not a volume. Block based file systems cannot be defragmented, only extent-based file systems can. Block based file systems like UFS or SYSV-1K FS do not have extents, which means that the word "fragmentation" doesn't make sense. You have superblock, inodes and data blocks. You don't have extents. AFAIK NTS is an extent-based file system and it can be defragmented. It is questionable, however, what will you gain by defragmenting. If your files have < n extents, their extent maps are cached in memory and need not to be re-read each time you access files. Hopefully, you're not using an NT system for DW, which means that your I/O pattern consists of random reads/writes, few blocks at a time. Fragmentation hurts you when you are doing frequent multiblock reads which are split into several I/O requests instead of being satisfied by a single large one. As defragmenter moves file extents around, database cannot be accessed, which essentially means that you must shut down the instance or it will hang. I don't know how much will you gain, but yes, you can defragment 130GB file system, even if it's on a Rabid Array of Inefficient Disks. As they say, size doesn't matter, it's the magic in the disk.
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mladen Gogala INET: mladen_at_wangtrading.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Wed Jan 21 2004 - 08:39:39 CST