From bb2a4905a1135c23ea88e3890d9955405b2f1a27 Mon Sep 17 00:00:00 2001 From: Sebastien GODARD Date: Tue, 9 Jul 2013 21:43:56 +0200 Subject: [PATCH] Update iostat manual page: Fix a small inaccuracy regarding %util field iostat manual page used to say that device saturation occured when the value of %util was close to 100%. This is true for devices serving requests serially but not necessariyl for devices able to serve multiple requests simultaneously. So update iostat manual page accordingly. --- man/iostat.in | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/man/iostat.in b/man/iostat.in index fc1dcc3..7a01af0 100644 --- a/man/iostat.in +++ b/man/iostat.in @@ -1,4 +1,4 @@ -.TH IOSTAT 1 "NOVEMBER 2012" Linux "Linux User's Manual" -*- nroff -*- +.TH IOSTAT 1 "JULY 2013" Linux "Linux User's Manual" -*- nroff -*- .SH NAME iostat \- Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions. @@ -268,7 +268,9 @@ This field will be removed in a future sysstat version. .RS Percentage of CPU time during which I/O requests were issued to the device (bandwidth utilization for the device). Device saturation occurs when this -value is close to 100%. +value is close to 100% for devices serving requests serially. +But for devices serving requests in parallel, such as RAID arrays and +modern SSDs, this number does not reflect their performance limits. .RE .RE .SH OPTIONS -- 2.50.1