I am fairly certain Linux software raid 1 does consider one of the drives as the master drive. Instructions to restore damaged arrays will indicate that. You can switch the drives around or move the slave to the master, but it still makes a distinction. Since a raid 1 is only about security, I doubt a proper raid 1 setup would allow you to read from both drives. There is the possibility that through some bug, a write and read could occur at the same time if the drives are on different ide controllers. I've run several Promise raid 1 arrays on most of the cards up through the SuperTrack series (which is an actual hardware raid card). I've never seen any sort of performance boost when compared to software raids or even regular ide/ata performance. But that is just me. Luke Harms lharms@xxxxxxxxxxx -----Original Message----- From: fedora-list-bounces@xxxxxxxxxx [mailto:fedora-list-bounces@xxxxxxxxxx] On Behalf Of Rodolfo J. Paiz Sent: Wednesday, June 16, 2004 12:06 PM To: For users of Fedora Core releases Subject: Re: Promise RAID-1 vs software RAID-1 At 10:39 6/16/2004, Alan Horn wrote: >Raid 1 is mirroring only. For data integrity reasons I can't see how they >could read from any but the master mirror. WAG alert: Once the two disks are synchronized, it sounds perfectly reasonable to writes to take the same amount of time (since all data has to be written to both drives), but for reads to be significantly faster by reading from both spindles. There really is no "master" in an equal set of two, I think. Both contain identical data, so you should be able to read from both. I think. By the way, the Promise cards *are* software RAID... all the real RAID computations are done by the driver using the computer's resources. The trick is that the binary driver for Linux is probably less mature and less flexible than Linux native software RAID, so I've always used Promise and HighPoint controllers simply as additional EIDE/ATA controllers and used Linux software RAID. Excellent results. Note that Linux software RAID is also capable of RAID-5, IIRC, which the Promise drivers are not. If you have the budget, I'd strongly recommend the 3Ware cards. Real hardware RAID, native Linux kernel support since 2.2.x, fast, very reliable, and not expensive. Cheers, -- Rodolfo J. Paiz rpaiz@xxxxxxxxxxxxxx http://www.simpaticus.com -- fedora-list mailing list fedora-list@xxxxxxxxxx To unsubscribe: http://www.redhat.com/mailman/listinfo/fedora-list
