Hi,
NetApp support has suggested us aligning partitions to improve performance, in short: starting sector must be divisible by 8. How can I move the start point in a misaligned partition -in production, with ext3- under Linux?
A screenshot with a misaligned (start=63s) and aligned (start=64s) partition is available at:
(If anyone is interested in this topic, NetApp has a good document explaining performance issues in misaligned partitions: "Best Practices for File System Alignment in Virtual Environments", http://goo.gl/EkBw)
I have tried using parted "resize + move" commands, but when moving start point a get this error:
(parted) resize Partition number? 1 Start? [64s]? End? [419425019s]? 419425018 (parted) move Partition number? 1 Start? 65 End? [419425019s]? 419425019 Error: Can't move a partition onto itself. Try using resize, perhaps?
Using fdisk 'b' command in expert mode ('move beginning of data in a partition') works, but it doesn't move the file system.. thanks!!
Regards,
AFAIK, you cannot do what you are trying to do. The point of file system alignment is to lay down the tracks on the entire disk so they align with the sector boundaries of the underlying device. Once everything is laid down and you have installed OS and written data, all of those blocks are already misaligned. You cannot move them unless you do a complete system backup, reformat, then restore the backup.
You might be able to fudge it by shrinking the partition down, then moving it to the end of the disk, then moving it again, this time to an aligned section of the disk. I can't imagine how long that would take, and is probably risky on a production system. To try this you would probably need at least half of the disk unused.
Unless you expect to see serious performance increases from this, it's not worth it. Chalk it up to learning and use that knowledge on your next installs. You should test out the process and performance gains on a development system first.
On Fri, Oct 22, 2010 at 7:00 AM, Santi Saez santisaez@woop.es wrote:
Hi,
NetApp support has suggested us aligning partitions to improve performance, in short: starting sector must be divisible by 8. How can I move the start point in a misaligned partition -in production, with ext3- under Linux?
A screenshot with a misaligned (start=63s) and aligned (start=64s) partition is available at:
(If anyone is interested in this topic, NetApp has a good document explaining performance issues in misaligned partitions: "Best Practices for File System Alignment in Virtual Environments", http://goo.gl/EkBw)
I have tried using parted "resize + move" commands, but when moving start point a get this error:
(parted) resize Partition number? 1 Start? [64s]? End? [419425019s]? 419425018 (parted) move Partition number? 1 Start? 65 End? [419425019s]? 419425019 Error: Can't move a partition onto itself. Try using resize, perhaps?
Using fdisk 'b' command in expert mode ('move beginning of data in a partition') works, but it doesn't move the file system.. thanks!!
Regards,
-- Santi Saez http://woop.es _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
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Brian Mathis -
Santi Saez