Software RAID

[cmccully]

Hi,

  What are the problems, if any of running raid and particularly software raid on the root folder. Also, I have setup a test system with software RAID 1 on SUSE 9. The system takes way, way, too long to copy files. About an hour to copy 5 gig from one folder to another. I would expect longer write times but this is excessive. Any ideas?

  By the way, I found something interesting when setting this up. The drives are 80 gig and the bios for this old system will not regognise them. So, I set the jumbers on the drives to clip them at 32 gig. System boots normally but Linux sees them as the full 80 gigs. You just have to love this operating system :).



cmccully

[the_oliver]

RAID is an administrators god send!  Odviously most people use RAID for an instant back up, if one disk fails the other simply takes over.  Again this can be done on lots of diffrent levels, the most common being a mirror raid.  Data is simply copied onto both disks identicaly, meening higher reliability and thus possibly grater up time.  A striped raid is another example, and used to have two disks acting as one larger one.  Often to alow higher availibilty. 

The one isue that can occour with raid is that if there is a coruption on one disk it will be copyed over onto the other.

Hardware RAID is almost always vastly superior, for the odvious resion that it does not rely on the softwere!  It will copy data from one disk to the other regardles of what the softwere is doing.  There for if the softwere is playing up your data will still be copied.  This does require a hardware RAID controler however.

[code]The system takes way, way, too long to copy files. About an hour to copy 5 gig from one folder to another. I would expect longer write times but this is excessive.[/code]

Realy you should not expet this!  The whole idea of it is that its instintainus.  When you origionaly set up the RAID there will be a long time to instiate it.  This is becase it has to ensure that the data on each disk is identical to start with.  Even the empty packets.  However once the system is running, there should be no noticible diffrence.  It is almost sertinatly down to the 80/32 problem.  Linux trying to copy data that the bios/disks are saying isnt there. (due to your clipping).  Could try a manual install and tell it what to copy?  Most importantly with linux its never the operating system always you!

After thought, do you have a resionable about of RAM in there?