>>>>> "nikolaus" == nikolaus <[EMAIL PROTECTED]> writes:
nikolaus> Of course can software RAID be faster than hardware RAID. nikolaus> But then you are not comparing the best offerings of each nikolaus> category. Software RAID is usually cheaper than hardware. nikolaus> But again you may be able to construct a product pairing nikolaus> where it is reverse. No... I admit... if you're willing to spend huge $$'s, there exist hardware solutions that outpace software. It usually means that you have hardware that is more powerful than your main system, though. Often more costly, too. nikolaus> raw versus file system is an old battle. raw is faster nikolaus> because it does not have the filesystem overhead. However, nikolaus> raw is a little harder to administer. Question is how much nikolaus> faster raw is and if it is worth the trouble. Numbers nikolaus> usually quoted are 10-20%. And here things may be changing nikolaus> as operating systems and chaching algorithems get better to nikolaus> mask the file system overhead. As I mentioned the question nikolaus> is mute for PostgeSQL because raw is currently not nikolaus> supported. Well... I don't think your raw write performance (in, say, FreeBSD) would be any more than 5% better than filesystem writing. Old filesystem overhead consisted of the in-order writes that were required to update filesystem metadata... which (consequently) was about 20% in-order (vs. un-ordered) writes. Softupdates (FreeBSD) only requires 1%-ish (or less) in-order writes (or to put it another way: 1% of writes chosen before they would otherwise happen). DAve. -- ============================================================================ |David Gilbert, Velocet Communications. | Two things can only be | |Mail: [EMAIL PROTECTED] | equal if and only if they | |http://daveg.ca | are precisely opposite. | =========================================================GLO================ ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
