Re: Informix on RAID-5

Jeff Craig wrote: > > Does anyone have any sage advice regarding implementing an Informix > database on a RAID-5 system? I am wondering how best to use Informix > fragmentation in light of the fact that RAID-5 has already striped the > data across disks. Since a RAID-5 "logical" drive is composed of several > physical drives over which data is spread by the RAID software, should > I try to fragment across logical drives? Should I skip Informix > fragmentation for RAID-based data? I am not planning on putting the > write-intensive stuff (logical and physical logs, temporary chunks, etc.) > on RAID-5. In order to make full use of the tuning parameters of OnLine you need to know where the data is being stored. As you say, with RAID you don't know this. Therefore, if you can set up a number of 'logical' drives, you can then treat these 'drives' as normal disk drives when allocating space to OnLine. This will give you the benefit of RAID with the ability to 'tune' OnLine. Setting up 'logical' drives generally means you need lots of disks to throw at RAID, because I 'think' RAID needs at least three disks per logical set, depending on the level you are implementing. If you can do this, then I would say 'yes' to fragmentation. I would also say put your logs and temporary tables (I presume you meant tables and not chunks) onto these 'logical' drives also. Just try to put, certainly the logs onto different 'drives'. Hope this isn't a complete ramble, -- Mark. +-------------------------------------------------------------------------+ |Mark D. Stock - The West Solutions Group http://www.west.co.za | | | |Email: marks@west.co.za +------------------------------------------------+ |Tel: +27 11 803 2151 |If it doesn't work... force it! | |Fax: +27 11 803 2189 |If it breaks... it needed replacing anyway! | |Cell: +27 83 250 2325 |Well, that's how I code anyway! | +------------------------+------------------------------------------------+