[20141229]关于linux文件系统的一些问题.txt

--昨天听别人讲linux文件系统的不是问题的问题,事情是这样别人的服务器raid5,出现一个坏盘,因为这台机器是dataguard,可以关机更
--换硬盘(也许认为这样比较保险).但是在启动的时候,fsck 要扫描文件系统,加上raid5在重构,结果几乎花了3个小时,才完成启动..

--顺便找1台机器查看:
# tune2fs -l /dev/mapper/vg_gxqyy-lv_home
tune2fs 1.41.12 (17-May-2010)
Filesystem volume name:  
Last mounted on:          /home
Filesystem UUID:          6b8570fc-432b-4008-8536-9a53c9402a2e
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      ext_attr resize_inode dir_index filetype sparse_super large_file
Filesystem flags:         signed_directory_hash
Default mount options:    (none)
Filesystem state:         not clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              26574848
Block count:              106288128
Reserved block count:     5314406
Free blocks:              43084974
Free inodes:              18020002
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      998
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8192
Inode blocks per group:   512
Filesystem created:       Thu Feb 20 17:33:28 2014
Last mount time:          Wed Nov 19 15:42:32 2014
Last write time:          Mon Dec 29 16:11:55 2014
Mount count:              2
Maximum mount count:      23
Last checked:             Wed Sep 24 13:05:12 2014
Check interval:           15552000 (6 months)
Next check after:         Mon Mar 23 13:05:12 2015
Lifetime writes:          896 GB
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               256
Required extra isize:     28
Desired extra isize:      28
Default directory hash:   half_md4
Directory Hash Seed:      6c67aa95-db53-469d-be9e-3f244041fe45

--可以发现最大安装次数23次,如果达到这个次数,下次启动要扫描文件系统.
Check interval:           15552000 (6 months)
Next check after:         Mon Mar 23 13:05:12 2015

--检查interval设置6个月,也就是Mon Mar 23 13:05:12 2015后如果启动机器,会自动调用fsck检查文件系统.

--我特地检查我们生产系统一台CentOS release 6.2 服务器,很明显centos已经取消了这个限制.
tune2fs -l /dev/...
Maximum mount count:      -1
Last checked:             Tue Jul  3 12:02:47 2012
Check interval:           0 ()

--实际上取消这个限制很简单,就是执行:
# tune2fs -c 0 -i 0  /dev/mapper/vg_gxqyy-lv_home
tune2fs 1.41.12 (17-May-2010)
Setting maximal mount count to -1
Setting interval between checks to 0 seconds

# tune2fs -l  /dev/mapper/vg_gxqyy-lv_home
tune2fs 1.41.12 (17-May-2010)
Filesystem volume name:  
Last mounted on:          /home
Filesystem UUID:          6b8570fc-432b-4008-8536-9a53c9402a2e
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      ext_attr resize_inode dir_index filetype sparse_super large_file
Filesystem flags:         signed_directory_hash
Default mount options:    (none)
Filesystem state:         not clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              26574848
Block count:              106288128
Reserved block count:     5314406
Free blocks:              43085500
Free inodes:              18019768
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      998
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         8192
Inode blocks per group:   512
Filesystem created:       Thu Feb 20 17:33:28 2014
Last mount time:          Wed Nov 19 15:42:32 2014
Last write time:          Mon Dec 29 16:19:31 2014
Mount count:              2
Maximum mount count:      -1
Last checked:             Wed Sep 24 13:05:12 2014
Check interval:           0 ()
Lifetime writes:          896 GB
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               256
Required extra isize:     28
Desired extra isize:      28
Default directory hash:   half_md4
Directory Hash Seed:      6c67aa95-db53-469d-be9e-3f244041fe45

--这样这种限制就会取消了.