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c372860d | 1 | .TH BLKDISCARD 8 "July 2014" "util-linux" "System Administration" |
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2 | .SH NAME |
3 | blkdiscard \- discard sectors on a device | |
4 | .SH SYNOPSIS | |
5 | .B blkdiscard | |
7154cc89 | 6 | [options] |
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7 | .RB [ \-o |
8 | .IR offset ] | |
9 | .RB [ \-l | |
10 | .IR length ] | |
d964b669 | 11 | .I device |
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12 | .SH DESCRIPTION |
13 | .B blkdiscard | |
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14 | is used to discard device sectors. This is useful for solid-state |
15 | drivers (SSDs) and thinly-provisioned storage. Unlike | |
b2cc2a7f | 16 | .BR fstrim (8), |
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17 | this command is used directly on the block device. |
18 | .PP | |
19 | By default, | |
20 | .B blkdiscard | |
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21 | will discard all blocks on the device. Options may be used to modify |
22 | this behavior based on range or size, as explained below. | |
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23 | .PP |
24 | The | |
25 | .I device | |
26 | argument is the pathname of the block device. | |
9f6bd5bd | 27 | .PP |
d964b669 | 28 | .B WARNING: All data in the discarded region on the device will be lost! |
d964b669 | 29 | .SH OPTIONS |
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30 | The |
31 | .I offset | |
32 | and | |
33 | .I length | |
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34 | arguments may be followed by the multiplicative suffixes KiB (=1024), |
35 | MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is | |
9f6bd5bd | 36 | optional, e.g., "K" has the same meaning as "KiB") or the suffixes |
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37 | KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB. |
38 | .TP | |
34fed3ff KZ |
39 | .BR \-f , " \-\-force" |
40 | Disable all checking. Since v2.36 the block device is open in exclusive mode (O_EXCL) | |
41 | by default to avoid collision with mounted filesystem or another kernel subsystem. | |
42 | The force option disables the exclusive access mode. | |
43 | .TP | |
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44 | .BR \-o , " \-\-offset \fIoffset" |
45 | Byte offset into the device from which to start discarding. The provided value | |
46 | will be aligned to the device sector size. The default value is zero. | |
47 | .TP | |
48 | .BR \-l , " \-\-length \fIlength" | |
49 | The number of bytes to discard (counting from the starting point). The provided value | |
50 | will be aligned to the device sector size. If the specified value extends past | |
9f6bd5bd | 51 | the end of the device, |
d964b669 | 52 | .B blkdiscard |
c372860d | 53 | will stop at the device size boundary. The default value extends to the end |
d964b669 | 54 | of the device. |
c372860d | 55 | .TP |
8f59654a KZ |
56 | .BR \-p , " \-\-step \fIlength" |
57 | The number of bytes to discard within one iteration. The default is to discard | |
58 | all by one ioctl call. | |
59 | .TP | |
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60 | .BR \-s , " \-\-secure" |
61 | Perform a secure discard. A secure discard is the same as a regular discard | |
62 | except that all copies of the discarded blocks that were possibly created by | |
63 | garbage collection must also be erased. This requires support from the device. | |
64 | .TP | |
7154cc89 KZ |
65 | .BR \-z , " \-\-zeroout" |
66 | Zero-fill rather than discard. | |
67 | .TP | |
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68 | .BR \-v , " \-\-verbose" |
69 | Display the aligned values of | |
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70 | .I offset |
71 | and | |
c372860d | 72 | .IR length . |
6bc4cc18 | 73 | If the \fB\-\-step\fR option is specified, it prints the discard progress every second. |
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74 | .TP |
75 | .BR \-V , " \-\-version" | |
76 | Display version information and exit. | |
77 | .TP | |
78 | .BR \-h , " \-\-help" | |
79 | Display help text and exit. | |
d964b669 | 80 | .SH AUTHOR |
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81 | .MT lczerner@redhat.com |
82 | Lukas Czerner | |
83 | .ME | |
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84 | .SH SEE ALSO |
85 | .BR fstrim (8) | |
86 | .SH AVAILABILITY | |
87 | The blkdiscard command is part of the util-linux package and is available | |
d673b74e | 88 | .UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ |
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89 | Linux Kernel Archive |
90 | .UE . |