Date: Wed, 14 May 2003 15:44:41 -0700 (PDT) From: Nate Lawson <nate@root.org> To: scsi@freebsd.org Subject: SCSI geometry calculation? Message-ID: <20030514151752.B79363@root.org>
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I am reviewing our current geometry calculation and have a few questions. Here is what I found in my review. Most drivers use >1G: 255/63, else 64/32. Exceptions are: * aac - >=2G: 255/63, >=1G 128/32, else 64/32 * aha - same * amr - >2G: 255/63, else 64/32 * asr - >4G: 255/63, >2G: 128/63, >1G: 65/63, else 64/32 * ata-raid - always 255/63 * bt - same as aha * ciss - 255/32 if fault_tolerance is invalid else what the logical drive reports. * mlx - if MLX_GEOM_256_63 set: 255/63, else 128/32. Since nothing seems to set mlx_geom, 128/32 is probably always used. * mly - same * pst - always 255/63 * twe - >2G: 255/63, else 64/32 Some of these seem to be bugs, especially for volumes exactly on a boundary (2G). Since many of the stranger ones are RAID controllers, they won't have to support drive portability to other controllers. What should actually be done in CALC_GEOMETRY? -Nate
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