On Sunday, 6 October 2002 at 11:30:16 -0700, Matthew Dillon wrote: > Yes, ccd is fairly light weight. 'man tuning' and 'man ccd' has > a lot of information on how to use it. I generally recommend > using a stripe size of 1152 for multitasking loads.
Sectors? Why particularly this value? > Only use a small/tiny stripe size if you need single-tasking > sequential performance (and even then you can take tune the > stripe to the drive's own caching capability). > > The biggest mistake most people make when using striping is that > they use too small a stripe size which causes nearly every read() or > write() to have to be split across multiple drives, which multiplies > the overhead, or causes sequential reads of medium sized files to > constantly seek multiple drives, destroying the effectiveness of having > two seekable heads in the first place. Pretty much exactly what I preach. One disadvantage of large stripes is that they require careful coding to optimize. I haven't looked at ccd, but I know a lot of cheap hardware RAID arrays always read an entire stripe at a time, which requires more memory and takes longer. Have you checked ccd for this? Greg -- See complete headers for address and phone numbers To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-current" in the body of the message
