Folks. My env is Solaris 10 update 8 amd64. Does LUN alignment matter when I''m creating zpool''s on disks (lun''s) with EFI labels and providing zpool the entire disk? I recently read some sun/oracle docs and blog posts about adjusting the starting sector for partition 0 (in format -e) to address lun alignment problems. However they never mention wether this matters for ZFS or not. In this scenario I have a lun provisioned from an STK 2540 and I put an EFI label on the disk. Then I modified partition 0 to start at sector 64 (tried 256 as well) and saved those changes. Once I do a zpool create the first sector get''s set to "34". Here is the format output with the adjusted sector partition> pr Current partition table (original): Total disk sectors available: 31440861 + 16384 (reserved sectors) Part Tag Flag First Sector Size Last Sector 0 usr wm 256 14.99GB 31440860 1 unassigned wm 0 0 0 2 unassigned wm 0 0 0 3 unassigned wm 0 0 0 4 unassigned wm 0 0 0 5 unassigned wm 0 0 0 6 unassigned wm 0 0 0 7 unassigned wm 0 0 0 8 reserved wu 31440861 8.00MB 31457244 now create the zpool zpool create testsector c5t6006016070B01E0052374B8B4CAFDE11d0 partition table after zpool create partition> pr Current partition table (original): Total disk sectors available: 31440861 + 16384 (reserved sectors) Part Tag Flag First Sector Size Last Sector 0 usr wm 34 14.99GB 31440861 I know i''m missing something here and any tips would be appreciated. TIA. Deet. -- This message posted from opensolaris.org
doh! It turns out the host in question is actually a Solaris 10 update 6 host. It appears that an Solaris 10 update 8 host actually sets the start sector at 256. So to simplify the question. If I''m using ZFS with EFI label and full disk do I even need to worry about lun alignment? I was all excited to do some benchmarking and now it appears that zfs will just do the right thing (assuming the right OS update). THanks. Deet. -- This message posted from opensolaris.org
On 01/07/2010 23:58, Derek Olsen wrote:> Folks. > My env is Solaris 10 update 8 amd64. Does LUN alignment matter when I''m creating zpool''s on disks (lun''s) with EFI labels and providing zpool the entire disk?http://blogs.sun.com/dlutz/entry/partition_alignment_guidelines_for_unified -- Darren J Moffat
On Jul 1, 2010, at 7:29 PM, Derek Olsen wrote:> doh! It turns out the host in question is actually a Solaris 10 update 6 host. It appears that an Solaris 10 update 8 host actually sets the start sector at 256.Yes, this is a silly bug, fixed years ago.> So to simplify the question. If I''m using ZFS with EFI label and full disk do I even need to worry about lun alignment? I was all excited to do some benchmarking and now it appears that zfs will just do the right thing (assuming the right OS update).It is not much of a problem on 512 byte sector HDDs. It is more of a performance problem on RAID arrays, especially if you are using RAID-5. But since it has been fixed for so long, we rarely see anyone reporting it as a problem. -- richard -- Richard Elling richard at nexenta.com +1-760-896-4422 ZFS and NexentaStor training, Rotterdam, July 13-15, 2010 http://nexenta-rotterdam.eventbrite.com/