Date: Fri, 11 May 2012 10:13:34 +0000 (UTC) From: Ulrich Spoerlein <uqs@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r235265 - head/share/man/man7 Message-ID: <201205111013.q4BADY9g076888@svn.freebsd.org>
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Author: uqs Date: Fri May 11 10:13:34 2012 New Revision: 235265 URL: http://svn.freebsd.org/changeset/base/235265 Log: Stop lying about default UFS blocksizes. This catches up with the year-old change to default blocksizes. Also reduce the variants of spelling gigabyte from 3 down to 2 (GB and GiB). Suggested by: arundel (about a year ago now ...) Modified: head/share/man/man7/tuning.7 Modified: head/share/man/man7/tuning.7 ============================================================================== --- head/share/man/man7/tuning.7 Fri May 11 09:46:17 2012 (r235264) +++ head/share/man/man7/tuning.7 Fri May 11 10:13:34 2012 (r235265) @@ -23,7 +23,7 @@ .\" .\" $FreeBSD$ .\" -.Dd October 16, 2010 +.Dd May 11, 2012 .Dt TUNING 7 .Os .Sh NAME @@ -148,15 +148,15 @@ If you do not use ports all that much an system source .Pq Pa /usr/src on the machine, you can get away with -a 1 gigabyte +a 1 GB .Pa /usr partition. However, if you install a lot of ports (especially window managers and Linux-emulated binaries), we recommend -at least a 2 gigabyte +at least a 2 GB .Pa /usr and if you also intend to keep system source -on the machine, we recommend a 3 gigabyte +on the machine, we recommend a 3 GB .Pa /usr . Do not underestimate the amount of space you will need in this partition, it can creep up and @@ -218,22 +218,22 @@ and .Em cylinders/group . .Pp .Fx -performs best when using 8K or 16K file system block sizes. -The default file system block size is 16K, +performs best when using 16K or 32K file system block sizes. +The default file system block size is 32K, which provides best performance for most applications, with the exception of those that perform random access on large files (such as database server software). Such applications tend to perform better with a smaller block size, although modern disk characteristics are such that the performance gain from using a smaller block size may not be worth consideration. -Using a block size larger than 16K +Using a block size larger than 32K can cause fragmentation of the buffer cache and lead to lower performance. .Pp The defaults may be unsuitable for a file system that requires a very large number of i-nodes or is intended to hold a large number of very small files. -Such a file system should be created with an 8K or 4K block size. +Such a file system should be created with an 4K, 8K, or 16K block size. This also requires you to specify a smaller fragment size. We recommend always using a fragment size that is 1/8 @@ -256,13 +256,13 @@ Do not use this option unless you are actually storing large files on the partition, because if you overcompensate you can wind up with a file system that has lots of free space remaining but cannot accommodate any more files. -Using 32768, 65536, or 262144 bytes/i-node is recommended. +Using 65536, 131072, or 262144 bytes/i-node is recommended. You can go higher but it will have only incremental effects on .Xr fsck 8 recovery times. For example, -.Dq Li "newfs -i 32768 ..." . +.Dq Li "newfs -i 65536 ..." . .Pp .Xr tunefs 8 may be used to further tune a file system. @@ -525,8 +525,8 @@ sysctl governs VFS read-ahead and is exp to pre-read if the heuristics algorithm decides that the reads are issued sequentially. It is used by the UFS, ext2fs and msdosfs file systems. -With the default UFS block size of 16 KiB, a setting of 32 will allow -speculatively reading up to 512 KiB. +With the default UFS block size of 32 KiB, a setting of 64 will allow +speculatively reading up to 2 MiB. This setting may be increased to get around disk I/O latencies, especially where these latencies are large such as in virtual machine emulated environments.
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