On 2010-01-08, at 14:43, H. Peter Anvin wrote:
On 01/08/2010 01:33 AM, Karel Zak wrote:
fdisk:
- the fdisk command aligns newly created partitions to
minimum_io_size
boundary ("minimum_io_size" is physical sector size or stripe
chunk
size on RAIDs).
- the fdisk command supports disks with alignment_offset now.
I think we should align, by default, much more aggressively than
that --
because frequently we just don't know what the real physical alignment
is (think of flash media, which uses large erase blocks underneath.)
Windows aligns partitions 1 MB boundaries by default now -- I think
that's probably a reasonably good idea, at least for any disk that's
not
tiny, say 256 MB or less.
I agree whole heartedly. We steer users very sharply away from using
partitions at all, because on h/w RAID devices the 512-byte offset
from fdisk completely kills RAID-5/6 performance.
Making the default minimum alignment for DOS/GPT partitions makes a
lot of sense, and LVM PEs should be on 1MB boundaries as well (I don't
think that is the case today either).
Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.
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