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minimum allocation size for devices. Use this information to automatically increase ZFS's minimum allocation size for new top-level vdevs to a value that more closely matches the optimum device allocation size. Use GEOM's stripesize attribute, if set, as the physical sector size of the GEOM. Calculate the minimum blocksize of each metaslab class. Use the calculated value instead of SPA_MINBLOCKSIZE (512b) when determining the likelyhood of compression yeilding a reduction in physical space usage. Report devices with sub-optimal block size configuration in "zpool status". Also properly fail attempts to attach devices with a logical block size greater than 8kB, since this will cause corruption to ZFS's label area. Sponsored by: Spectra Logic Corporaion MFC after: 2 weeks Background ========== Many modern devices use physical allocation units that are much larger than the minimum logical allocation size accessible by external commands. Two prevalent examples of this are 512e disk drives (512b logical sector, 4K physical sector) and flash devices (512b logical sector, 4K or larger allocation block size, and 128k or larger erase block size). Operations that modify less than the physical sector size result in a costly read-modify-write or garbage collection sequence on these devices. Simply exporting the true physical sector of the device to ZFS would yield optimal performance, but has two serious drawbacks: 1) Existing pools created with devices that have different logical and physical block sizes, but were configured to use the logical block size (e.g. because the OS version used for pool construction reported the logical block size instead of the physical block size) will suddenly find that the vdev allocation size has increased. This can be easily tolerated for active members of the array, but ZFS would prevent replacement of a vdev with another identical device because it now appears that the smaller allocation size required by the pool is not supported by the new device. 2) The device's physical block size may be too large to be supported by ZFS. The optimal allocation size for the vdev may be quite large. For example, a RAID controller may export a vdev that requires read-modify-write cycles unless accessed using 64k aligned/sized requests. ZFS currently has an 8k minimum block size limit. Reporting both the logical and physical allocation sizes for vdevs solves these problems. A device may be used so long as the logical block size is compatible with the configuration. By comparing the logical and physical block sizes, new configurations can be optimized and administrators can be notified of any existing pools that are sub-optimal. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/spa.h: Add the SPA_ASHIFT constant. ZFS currently has a hard upper limit of 13 (8k) for ashift and this constant is used to both document and enforce this limit. sys/cddl/contrib/opensolaris/uts/common/sys/fs/zfs.h: Add the VDEV_AUX_ASHIFT_TOO_BIG error code. Add fields for exporting the configured, logical, and physical ashift to the vdev_stat_t structure. Add VDEV_STAT_VALID() macro which can be used to verify the presence of required vdev_stat_t fields in nvlist data. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c: Provide a SYSCTL_PROC handler for "max_auto_ashift". Since the limit is only referenced long after boot when a create operation occurs, there's no compelling need for it to be a boot time configurable tunable. This also allows the validation code for the max_auto_ashift value to be contained within the sysctl handler. Populate the new fields in the vdev_stat_t structure. Fail vdev opens if the vdev reports an ashift larger than SPA_MAXASHIFT. Propogate vdev_logical_ashift and vdev_physical_ashift between child and parent vdevs as is done for vdev_ashift. In vdev_open(), restore code that fails opens for devices where vdev_ashift grows. This can only happen now if the device's logical ashift grows, which means it really isn't safe to use the device. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/vdev_impl.h: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_file.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_geom.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_mirror.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_missing.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_raidz.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev_root.c: Update the vdev_open() API so that both logical (what was just ashift before) and physical ashift are reported. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/vdev_impl.h: Add two new fields, vdev_physical_ashift and vdev_logical_ashift, to vdev_t. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/vdev.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa_config.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/spa.c: Add vdev_ashift_optimize(). Call it anytime a new top-level vdev is allocated. cddl/contrib/opensolaris/cmd/zpool/zpool_main.c: Add text for the VDEV_AUX_ASHIFT_TOO_BIG error. For each sub-optimally configured leaf vdev, report configured and native block sizes. cddl/contrib/opensolaris/cmd/zpool/zpool_main.c: cddl/contrib/opensolaris/lib/libzfs/common/libzfs.h: cddl/contrib/opensolaris/lib/libzfs/common/libzfs_status.c: Introduce a new zpool status: ZPOOL_STATUS_NON_NATIVE_ASHIFT. This status is reported on healthy pools containing vdevs configured to use a block size smaller than their reported physical block size. cddl/contrib/opensolaris/lib/libzfs/common/libzfs_status.c: Update find_vdev_problem() and supporting functions to provide the full vdev_stat_t structure to problem checking routines, and to allow decent into replacing vdevs. Add a vdev_non_native_ashift() validator which is used on the full vdev tree to check for ZPOOL_STATUS_NON_NATIVE_ASHIFT. cddl/contrib/opensolaris/lib/libzpool/common/kernel.c: cddl/contrib/opensolaris/lib/libzpool/common/sys/zfs_context.h: Enhance sysctl userland stubs now that a SYSCTL_PROC handler is used in vdev.c. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab_impl.h: When the group membership of a metaslab class changes (i.e. when a vdev is added or removed from a pool), walk the group list to determine the smallest block size currently available and record this in the metaslab class. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/metaslab.h: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/metaslab.c: Add the metaslab_class_get_minblocksize() accessor. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/zio_compress.h: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio_compress.c: sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c: In zio_compress_data(), take the minimum blocksize as an input parameter instead of assuming SPA_MINBLOCKSIZE. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c: In l2arc_compress_buf(), pass SPA_MINBLOCKSIZE as the minimum blocksize of the device. The l2arc code performs has it's own code for deciding if compression is worth while, so this effectively disables zio_compress_data() from second guessing the original decision. sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zio.c: In zio_write_bp_init(), use the minimum blocksize of the normal metaslab class when compressing data.
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``world'' target should only be used in cases where the source tree has not changed from the currently running version. See: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/makeworld.html for more information, including setting make(1) variables. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. cddl Various commands and libraries under the Common Development and Distribution License. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html