On Monday 26 November 2001 11:02 am, Wolfgang Bornath wrote: > Hi, > > a german user asks if there is anyone using the promise fastrak 100 > lite raid controller which is onboard a MSI K7 mobo. He has a raid of > 2 Maxtor 40GByte hds and wants to switch to Mandrake Linux if this > raid is supported. > > wobo
Not supported unless you are an expert... These RAID controllers are like unto WinModems--really software does the job, which is not a bad thing because it does increase performance, but the drivers just aren't there for linux. Here is an article I wrote for a LUG about the devices. OK if you want a hardware IDE RAID, there is one, and it is OS transparent. http://www.arcoide.com/productspages/products.html There is nothing else that is a pure hardware IDE RAID. Now we have controllers from CMD, Promise, Highpoint, and at least one other plus 3ware. The 3ware controller, while it existed, had GPL drivers. Those are all to some extent Software RAID. Here's how tey do it: Assume this line is your disk space: M----------------------------- where M is te master boot record. After the controller does its thing, MR--------------------------R where the R are date and timestamp info. Also your drive has been destroked in the BIOS to protect those areas. There is also a little info there to toggle which lie the controller will tell the system about wat is real and what is not. The result is that you have precisely one RAID extent, because of this design. The R at the front of the disk is useless because LILO stomps all over it, but the one at the other end is the one used (originally, only the beginning was used so very early controllers are rotally incompatible with linux and in fact their RAIDs are destroyed by an attempted install.) OK let's look at the software RAIDs "Hardware " Cards Linux Software RAID Extents 1 >16 RAID Types 0, 1 0+1 0,1,4,5 Identical drives Yes Irrelevant Volume mgr No Volumes can be pieces of up to 16 drives Setup at install No, requires kernel mods Yes Cost $30-100 extra Your time Journaling filesystems will work with both. If you really want to use the RAID controller in RAID mode, even after all of this, there is some _experimental_ software to do so here: http://people.redhat.com/arjanv/pdcraid/ Of course, this is not for the faint of heart. The one advantage of having this software probably is with Promise FastTrak controllers which do not fully work as IDE controllers in linux. The most useful feature is compatibility with Windows RAID for file exchange on a stand-alone dual-boot system. (A small network has better alternatives). RAID0 does perform better for two drives as far as access time goes. It performs even better if the drives are on different IDE channels, which is achievable with linux Software RAID, but not with the controllers I have tested. Finally, all of the IDE-RAID controllers are closed-source at this time. They may all admit that linux software RAID is better in implementation than theirs, but they are sorely afraid of giving their competitiors advantage in the Windows market. WinRAIDs, anyone? Civileme
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