thomas62186218@xxxxxxx wrote: > Hi everyone, > > I too was seeing miserable read-performance with LVM2 volumes on top of > md RAID 10's on my Ubuntu 8.04 64-bit machine. My RAID 10 has 12 x 300GB > 15K SAS drives on a 4-port LSI PCIe SAS controller. > > I use: > blockdev --setra 65536 /dev/md0 > > And this dramatically increased my RAID 10 read performance. > > You MUST do the same for your LVM2 volumes for them to see a comparable > performance boost. > > blockdev --setra 65536 /dev/mapper/raid10-testvol > This is incorrect. Only the readahead setting of the _last_ block device matters. So in case you have a raid6 of 10 drives, with LUKS on top, with LVM on top - only the readahead settings of the individual LVs matter, nothing further down the chain is consulted. -- 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
