On Tue, Aug 31, 2010 at 12:47:49PM -0700, Brandon High wrote: > On Mon, Aug 30, 2010 at 3:05 PM, Ray Van Dolson <rvandol...@esri.com> wrote: > > I want to "fix" (as much as is possible) a misalignment issue with an > > X-25E that I am using for both OS and as an slog device. > > It's pretty easy to get the alignment right > > fdisk uses a default of 63/255/*, which isn't easy to change. This > makes each cylinder ( 63 * 255 * 512b ). You want ( $cylinder_offset > ) * ( 63 * 255 * 512b ) / ( $block_alignment_size ) to be evenly > divisible. For a 4k alignment you want the offset to be 8. > > With fdisk, create your SOLARIS2 partition that uses the entire disk. > The partition will be from cylinder 1 to whatever. Cylinder 0 is used > for the MBR, so it's automatically un-aligned. > > When you create slices in format, the MBR cylinder isn't visible, so > you have to subtract 1 from the offset, so your first slice should > start on cylinder 7. Each additional cylinder should start on a > multiple of 8, minus 1. eg: 63, 1999, etc. > > It doesn't matter if the end of a slice is unaligned, other than to > make aligning the next slice easier. > > -B
Thanks Brandon. Just a follow-up to my original post... unfortunately I couldn't try aligning the slice on the SSD I was also using for slog/ZIL. The slog/ZIL slice was too small to be added to the ZIL mirror as the disk we'd thrown in the system bypassing the expander was being used completely (via EFI label). Still wanted to test, however, so I pulled one of the drives from my rpool, and added the entire disk to my mirror. This uses the EFI label and aligns everything correctly. Unit Attention errors immediately began showing up. I pulled that drive from the ZIL mirror and then used one of my two L2ARC drives (also X-25E's) in the same fashion. Same problem. So I believe the problem is still expander related moreso than alignment related. Too bad. Ray _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
