On Thursday August 4, djani22@xxxxxxxxxxxxx wrote: > Hi list, Neil! > > I have a little question because I'v got some performance problem... What performance problem? > Is the RAID5 do any type of headahead with the default config? Technically: no. raid5 itself doesn't do readahead. The filesystem or VM layer does read-ahead. The block device can suggest the sort of read-ahead size which might be appropriate. > It is possible to disable the readahead? (if it is.) This has been answered - man blockdev But you almost certainly don't want to. > Or just the io_sched do that on the disks? > > How can I disable the whole headahead on top of the RAID5 array? > > The RAID5 can do multiple small (<4kb) reads of disks for the multithreaded > read requests? > (chunk size is 32k) Multiple small random read requests should evenly distribute over all drives and give reasonable performance. But again, you haven't said what your problem is.... NeilBrown > > Thanks for helping! > > Janos - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
