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From: agk@sourceware.org To: lvm-devel@redhat.com, lvm2-cvs@sourceware.org Subject: LVM2/man dmsetup.8.in Date: Wed, 30 Nov 2011 22:32:00 -0000 [thread overview] Message-ID: <20111130223238.9766.qmail@sourceware.org> (raw) CVSROOT: /cvs/lvm2 Module name: LVM2 Changes by: agk@sourceware.org 2011-11-30 22:32:37 Modified files: man : dmsetup.8.in Log message: refer to kernel docs for target info FIXME thin still missing Patches: http://sourceware.org/cgi-bin/cvsweb.cgi/LVM2/man/dmsetup.8.in.diff?cvsroot=lvm2&r1=1.46&r2=1.47 --- LVM2/man/dmsetup.8.in 2011/11/13 01:41:57 1.46 +++ LVM2/man/dmsetup.8.in 2011/11/30 22:32:37 1.47 @@ -532,16 +532,13 @@ To wait until the next event is triggered, use \fBinfo\fP to find the last event number. .SH TABLE FORMAT -// FIXME Rewrite safely (a lot of work) or remove. Each line of the table specifies a single target and is of the form: .P .I logical_start_sector num_sectors .B target_type .RI < target_args > .P -There are currently three simple target types available (linear, -striped, error) together with more complex optional ones that implement -e.g. snapshots and mirrors. +Simple target types and <target_args> include: .HP .B linear .I destination_device start_sector @@ -572,83 +569,49 @@ Errors any I/O that goes to this area. Useful for testing or for creating devices with holes in them. .TP +.B zero +.br +Returns blocks of zeroes on reads. Any data written is discarded silently. +This is a block-device equivalent of the /dev/zero character-device data sink +described in \fBnull(4)\fP. +.P +More complex targets include: +.TP .B crypt -.I cipher key iv_offset destination offset -.RI [ num_params -.RI < params >] .br -Target for transparent encryption of block devices -using the kernel crypto API. +Transparent encryption of block devices using the kernel crypto API. .TP .B delay -.I read_device read_offset read_delay -.RI [ write_device -.I write_offset -.IR write_delay ] .br -Creates mapping that "delays" reads and/or writes -to different devices. +Delays reads and/or writes to different devices. Useful for testing. .TP .B flakey -.I destination_device start_sector up_interval -.I down_interval -.RI [ num_features -.RI [< feature_arguments >]] -.br -Creates the same mapping as the linear target except -that it exhibits unreliable behaviour periodically. -Useful for simulating failing devices for testing -purposes. +.br +Creates a similar mapping to the linear target but +exhibits unreliable behaviour periodically. +Useful for simulating failing devices when testing. .TP .B mirror -.I log_type num_logargs -.RI < logargs > -.I num_devices -.RI < device -.IR offset >+ .br -Creates mirror mapping target for mirrored logical devices. +Mirrors data across two or more devices. .HP .B multipath -.I num_features -.RI < features > -.I num_handle_args -.RI < handle_args > -.I num_path_groups -.I path_group -.RI < path_group_args1\.\.N > -.br -Creates multipath mapping. -.TP -.BR raid1 | raid4 | raid5_ { la | ra | ls | rs }| raid6_ { zr | mr | nc } -.I num_raid_params -.RI < raid_params > -.I num_raid_devs -.RI < metadata_device -.IR device >+ -.br -Creates RAID "bridge" mapping between DM and MD. -It allows the MD RAID drivers to be -accessed using a device-mapper interface. -.HP -.B snapshot -.I origin_device cow_device persistant chunksize .br -.HP -.B snapshot-merge -.I origin_device cow_device persistant chunksize +Mediates access through multiple paths to the same device. +.TP +.BR raid .br +Offers an interface to the kernel's software raid driver, md. .HP -.B snapshot-origin -.I origin_device -.br -Supports device snapshots. -.TP -.B zero +.B snapshot .br -Returns always zeroed data on reads and silently drops writes. -This is similar behavior to /dev/zero, but as a block-device instead -of a character device. +Supports snapshots of devices. +.P +To find out more about the various targets and their table formats and status +lines, please read the files in the Documentation/device-mapper directory in +the kernel source tree. +(Your distribution might include a copy of this information in the +documentation directory for the device-mapper package.) .SH EXAMPLES
next reply other threads:[~2011-11-30 22:32 UTC|newest] Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-11-30 22:32 agk [this message] -- strict thread matches above, loose matches on Subject: below -- 2012-02-15 12:25 prajnoha 2011-11-13 1:41 agk 2011-03-10 13:11 mbroz 2010-02-15 16:32 prajnoha 2009-11-06 1:41 agk 2009-10-22 13:12 prajnoha 2009-04-23 12:20 agk
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