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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 | |
39 | .BR \-o , " \-\-offset \fIoffset" | |
40 | Byte offset into the device from which to start discarding. The provided value | |
41 | will be aligned to the device sector size. The default value is zero. | |
42 | .TP | |
43 | .BR \-l , " \-\-length \fIlength" | |
44 | The number of bytes to discard (counting from the starting point). The provided value | |
45 | will be aligned to the device sector size. If the specified value extends past | |
9f6bd5bd | 46 | the end of the device, |
d964b669 | 47 | .B blkdiscard |
c372860d | 48 | will stop at the device size boundary. The default value extends to the end |
d964b669 | 49 | of the device. |
c372860d | 50 | .TP |
8f59654a KZ |
51 | .BR \-p , " \-\-step \fIlength" |
52 | The number of bytes to discard within one iteration. The default is to discard | |
53 | all by one ioctl call. | |
54 | .TP | |
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55 | .BR \-s , " \-\-secure" |
56 | Perform a secure discard. A secure discard is the same as a regular discard | |
57 | except that all copies of the discarded blocks that were possibly created by | |
58 | garbage collection must also be erased. This requires support from the device. | |
59 | .TP | |
7154cc89 KZ |
60 | .BR \-z , " \-\-zeroout" |
61 | Zero-fill rather than discard. | |
62 | .TP | |
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63 | .BR \-v , " \-\-verbose" |
64 | Display the aligned values of | |
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65 | .I offset |
66 | and | |
c372860d | 67 | .IR length . |
6bc4cc18 | 68 | If the \fB\-\-step\fR option is specified, it prints the discard progress every second. |
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69 | .TP |
70 | .BR \-V , " \-\-version" | |
71 | Display version information and exit. | |
72 | .TP | |
73 | .BR \-h , " \-\-help" | |
74 | Display help text and exit. | |
d964b669 | 75 | .SH AUTHOR |
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76 | .MT lczerner@redhat.com |
77 | Lukas Czerner | |
78 | .ME | |
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79 | .SH SEE ALSO |
80 | .BR fstrim (8) | |
81 | .SH AVAILABILITY | |
82 | The blkdiscard command is part of the util-linux package and is available | |
d673b74e | 83 | .UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/ |
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84 | Linux Kernel Archive |
85 | .UE . |