From 27c3e539b65e1606a72c79e3b1c154b77daeb5e5 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Tue, 21 Apr 2009 22:18:19 -0400 Subject: [PATCH] Explain the significance of the 'T' attribute in the chattr.1 man page Addresses-Debian-Bug: #365619 Signed-off-by: "Theodore Ts'o" --- misc/chattr.1.in | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/misc/chattr.1.in b/misc/chattr.1.in index 960f058..d1c4cb5 100644 --- a/misc/chattr.1.in +++ b/misc/chattr.1.in @@ -114,8 +114,14 @@ the changes are written synchronously on the disk; this is equivalent to the `sync' mount option applied to a subset of the files. .PP A directory with the 'T' attribute will be deemed to be the top of -directory hierarchies for the purposes of the Orlov block allocator -(which is used in on systems with Linux 2.5.46 or later). +directory hierarchies for the purposes of the Orlov block allocator. +This is a hint to the block allocator used by ext3 and ext4 that the +subdirectories under this directory are not related, and thus should be +spread apart for allocation purposes. For example it is a very good +idea to set the 'T' attribute on the /home directory, so that /home/john +and /home/mary are placed into separate block groups. For directories +where this attribute is not set, the Orlov block allocator will try to +group subdirectories closer together where posible. .PP A file with the 't' attribute will not have a partial block fragment at the end of the file merged with other files (for those filesystems which -- 1.8.3.1