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author | Giorgos Keramidas <keramida@FreeBSD.org> | 2002-04-16 05:35:56 +0000 |
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committer | Giorgos Keramidas <keramida@FreeBSD.org> | 2002-04-16 05:35:56 +0000 |
commit | 6002cc3e6fe0f6027c0be93727dc77afa32374d2 (patch) | |
tree | 36d5bcca8084e62b9f446d9c5aba11d7e774c494 /sbin | |
parent | e5ee83db1dbb01f5be80a743b1a33c6d0e70d485 (diff) | |
download | src-6002cc3e6fe0f6027c0be93727dc77afa32374d2.tar.gz src-6002cc3e6fe0f6027c0be93727dc77afa32374d2.zip |
Expand the reserved space section. Explain how the amount of reserved
space can affect performance.
Submitted by: David Schultz <dschultz@uclink.Berkeley.EDU>
Notes
Notes:
svn path=/head/; revision=94818
Diffstat (limited to 'sbin')
-rw-r--r-- | sbin/tunefs/tunefs.8 | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/sbin/tunefs/tunefs.8 b/sbin/tunefs/tunefs.8 index 89a6d3f5b8eb..c160e13edf35 100644 --- a/sbin/tunefs/tunefs.8 +++ b/sbin/tunefs/tunefs.8 @@ -100,13 +100,21 @@ Specify the expected average file size. Specify the percentage of space held back from normal users; the minimum free space threshold. The default value used is 8%. -This value can be set to zero, however up to a factor of three -in throughput will be lost over the performance obtained at a 10% -threshold. +Note that lowering the threshold can adversely affect performance: +.Pp +.Bl -bullet +.It Settings of 5% and less force space optimization to always be used which will greatly increase the overhead for file writes. -Note that if the value is raised above the current usage level, +.It +The filesystem's ability to avoid fragmentation will be reduced +when the total free space, including the reserve, drops below 15%. +As free space approaches zero, throughput can degrade by up to a +factor of three over the performance obtained at a 10% threshold. +.El +.Pp +If the value is raised above the current usage level, users will be unable to allocate files until enough files have been deleted to get under the higher threshold. .It Fl n Ar enable | disable |