Martin Matuska b28e57cb82 Allow setting a lower ashift with -o ashift ... Previous patches have allowed you to set an increased ashift to avoid doing 512b IO with 4k sector devices. However, it was not possible to set the ashift lower than the reported physical sector size even when a smaller logical size was supported. In practice, there are several cases where settong a lower ashift is useful: * Most modern drives now correctly report their physical sector size as 4k. This causes zfs to correctly default to using a 4k sector size (ashift=12). However, for some usage models this new default ashift value causes an unacceptable increase in space usage. Filesystems with many small files may see the total available space reduced to 30-40% which is unacceptable. * When replacing a drive in an existing pool which was created with ashift=9 a modern 4k sector drive cannot be used. The 'zpool replace' command will issue an error that the new drive has an 'incompatible sector alignment'. However, by allowing the ashift to be manual specified as smaller, non-optimal, value the device may still be safely used. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #1381 Closes #1328 Issue #967 Issue #548		2013-04-12 10:50:46 -07:00
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avl	Add script for builtin module building.	2012-07-26 13:45:09 -07:00
nvpair	Illumos #2619 and #2747	2013-01-08 10:35:35 -08:00
unicode	Add script for builtin module building.	2012-07-26 13:45:09 -07:00
zcommon	Add snapdev=[hidden|visible] dataset property	2013-03-05 12:37:54 -08:00
zfs	Allow setting a lower ashift with -o ashift	2013-04-12 10:50:46 -07:00
zpios	Refresh links to web site	2013-03-06 15:46:41 -08:00
.gitignore	gitignore: anchor entries at their respective directory	2013-04-02 10:50:17 -07:00
Makefile.in	Add KMODDIR to install target	2013-03-06 15:46:40 -08:00