From 9d36fe9a23ba9180eec31398ef87f2c96258dd95 Mon Sep 17 00:00:00 2001 From: keramida Date: Tue, 16 Apr 2002 05:35:56 +0000 Subject: Expand the reserved space section. Explain how the amount of reserved space can affect performance. Submitted by: David Schultz --- sbin/tunefs/tunefs.8 | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) (limited to 'sbin/tunefs') 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 -- cgit v1.1