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authorkeramida <keramida@FreeBSD.org>2002-04-16 05:35:56 +0000
committerkeramida <keramida@FreeBSD.org>2002-04-16 05:35:56 +0000
commit9d36fe9a23ba9180eec31398ef87f2c96258dd95 (patch)
tree36d5bcca8084e62b9f446d9c5aba11d7e774c494 /sbin/tunefs
parenta1c1001cdd19597ad6afb19c938402f9d6fc7cf0 (diff)
downloadFreeBSD-src-9d36fe9a23ba9180eec31398ef87f2c96258dd95.zip
FreeBSD-src-9d36fe9a23ba9180eec31398ef87f2c96258dd95.tar.gz
Expand the reserved space section. Explain how the amount of reserved
space can affect performance. Submitted by: David Schultz <dschultz@uclink.Berkeley.EDU>
Diffstat (limited to 'sbin/tunefs')
-rw-r--r--sbin/tunefs/tunefs.816
1 files changed, 12 insertions, 4 deletions
diff --git a/sbin/tunefs/tunefs.8 b/sbin/tunefs/tunefs.8
index 89a6d3f..c160e13 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
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