> Is the LVM volume aligned to the RAID stripe? Is their a partition atop > the RAID LUN and under LVM? Is the partition aligned? Why LVM anyway? Yes, it is aligned. I followed the advice from <http://www.mysqlperformanceblog.com/2011/06/09/aligning-io-on-a-hard-disk-raid-the-theory/>. Why LVM? Because we use it on lots of servers, and there is some value to having a somewhat similar setup in development as in production. I’ve done similar tests time and again with LVM and without, and I’ve never ever measured a significant difference. I haven’t re-tested it this time, true, but I would be surprised if it would magically behave completely differently this time. > The devil is always in the details. Were you using partitions and LVM > with the RAID1 concat tesing? With the free space testing? I used LVM linear for the concatenation – one volume group made from 3 physical volumes. The pvols were on primary partitions. The one-volume RAID 6 is set up similarly; from only one pvol of course. > I assumed you were directly formatting the LUN with XFS. With LVM and > possibly partitions involved here, that could explain some of the > mediocre performance across the board, with both EXT4 and XFS. If one > wants maximum performance from their filesystem, one should typically > stay away from partitions and LVM, and any other layers that can slow IO > down. I don’t want maximum performance, I want acceptable performance ;). This means, I am satisfied with 80% or more of what’s possible, but I’m not satisfied with 15%. _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
