Hi all, sorry if I ask an old question, but I couldn't find a definite answer on the web. I just bought some new computer (shuttle SN85 / AMD 64 / nforce3 / 2 sata HD), which should be configured as raid 1 (mirroring). Question is should I simply use Linux Software Raid or should I try to use dmraid and the nforce chip (Fedora Core 4 and RHEL WS 4, both seem quite difficult to configure)? I know, many people recommend Linux md/sw raid. Arjan argued for this several times and based his argument mainly on theoretical considerations. There are some findings (e.g. http://www.jab.org/raid-bench/) which show that md raid 1 does not perform worse than a single disk. Others found that Linux md raid performs better as even a real hardware raid ( http://www.chemistry.wustl.edu/~gelb/castle_raid.html , http://spamaps.org/raidtests.php ). But the several fake raid controller seem to differ quite a lot. OK. I tried to copy a 700 mb iso file and found: disk -> disk: 19 sec. disk -> raid: 39 sec. Writing to the raided partition took roughly twice the time. Seems the kernel itself has to write the file two times one after another. Question: - Can/Could/Should the usage of dmraid/device mapper give a better write performance as the md raid? (I hope the chip can write in parallel, but absolutely don't know anything about it's technical details and could find any information) - If I use md/SW raid should I nevertheless activate the raid functionality in BIOS? - If I later want to test dmraid, can I use the partitions and filesystems, configured for md/sw raid (with the auto raid block), or have I to clear and reconfigure the disks anyway? Any information highly appreciated. Thanks in advance Peter _______________________________________________ Ataraid-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ataraid-list
