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Improve wording for -E and -t flags. -E never writes the entire disk,

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so don't imply that. Note that if BIO_DELETE isn't supported, the
operation will fail (as opposed to writing the entire disk with
zeros). Thin storage also benefits from trim. List more accurate
reason why trim helps flash-memory.
This commit is contained in:
Warner Losh 2017-07-07 16:54:18 +00:00
parent 9f861cfc6b
commit 1e001b99a5
1 changed files with 8 additions and 8 deletions
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@ -79,11 +79,9 @@ The following options define the general layout policies:
.It Fl E
Erase the content of the disk before making the filesystem.
The reserved area in front of the superblock (for bootcode) will not be erased.
.Pp
This option is only relevant for flash based storage devices that use
wear-leveling algorithms.
.Pp
Erasing may take a long time as it writes to every sector on the disk.
Erasing is only relevant to flash-memory or thinly provisioned devices.
Erasing may take a long time.
If the device does not support BIO_DELETE, the command will fail.
.It Fl J
Enable journaling on the new file system via gjournal.
See
@ -264,9 +262,11 @@ Turn on the TRIM enable flag.
If enabled, and if the underlying device supports the BIO_DELETE
command, the file system will send a delete request to the underlying
device for each freed block.
The trim enable flag is typically set when the underlying device
uses flash-memory as the device can use the delete command to
pre-zero or at least avoid copying blocks that have been deleted.
The trim enable flag is typically set for flash-memory devices to
reduce write amplification which reduces wear on write-limited
flash-memory and often improves long-term performance.
Thinly provisioned storage also benefits by returning unused blocks to
the global pool.
.El
.Pp
The following options override the standard sizes for the disk geometry.