linux挂载磁盘就变只读如何解决

Linux系统挂载存储变成只读的解决方案：

1、mount:

用于查看哪个模块输入只读，一般显示为：

[root@localhost ~]# mount

/dev/cciss/c0d0p2 on / type ext3 (rw)

proc on /proc type proc (rw)

sysfs on /sys type sysfs (rw)

devpts on /dev/pts type devpts (rw,gid=5,mode=620)

/dev/cciss/c0d0p7 on /home type ext3 (rw)

/dev/cciss/c0d0p6 on /var type ext3 (rw)

/dev/cciss/c0d0p3 on /usr type ext3 (rw)

/dev/cciss/c0d0p1 on /boot type ext3 (rw)

tmpfs on /dev/shm type tmpfs (rw)

none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)

sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)

/dev/dm-0 on /home/book/upload/BookFile1 type ext3 (rw)

/dev/dm-1 on /home/book/upload/BookFile2 type ext3 (rw)

/dev/dm-2 on /backup type ext3 (rw)

/dev/dm-3 on /home/book/upload/BookFile3 type ext3 (ro)

2、如果发现有ro，就重新mount，或者umount以后再remount

3、umount /dev/dm-3

如果发现有提示“device is busy”，找到是什么进程使得他busy

fuser -m /mnt/data 将会显示使用这个模块的pid

fuser -mk /mnt/data 将会直接kill那个pid

然后重新mount即可。

4、还有一种方法是直接remount，命令为

mount -o rw,remount /mnt/data。

一、多路径解释

多路径，顾名思义就是有多种选择的路径。在SAN或IPSAN环境，主机和存储之间外加了光纤交换机，这就导致主机和存储之间交换速度和效率增强，一条路径肯定是不行的，也是不安全不稳定的。多路径就是要来解决从主机到磁盘之间最快，最高效的问题。主要实现如下几个功能

故障的切换和恢复

IO流量的负载均衡

磁盘的虚拟化

多路径之前一直是存储厂商负责解决，竟来被拆分出来单独卖钱了。

构架基本是这样的：存储，多路径软件，光纤交换机，主机，主机系统。

二、LINUX下的multipath

1、查看是否自带安装？

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[root@web2 multipath]# rpm -qa|grep device

device-mapper-1.02.39-1.el5

device-mapper-1.02.39-1.el5

device-mapper-multipath-0.4.7-34.el5

device-mapper-event-1.02.39-1.el5

[root@web2 multipath]#

2、安装

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rpm -ivh device-mapper-1.02.39-1.el5.rpm#安装映射包

rpm -ivh device-mapper-multipath-0.4.7-34.el5.rpm #安装多路径包

外加加入开机启动

chkconfig –level 2345 multipathd on #设置成开机自启动multipathd

lsmod |grep dm_multipath #来检查安装是否正常

3、配置

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# on the default devices.

blacklist {

devnode "^(ram|raw|loop|fd|md|dm-|sr|sr|scd|st)[0-9]*"

devnode "^hd[a-z]"

}

devices {

device {

vendor "HP"

path_grouping_policy multibus

features "1 queue_if_no_path"

path_checker readsector()

failback immediate

}

}<br><br>完整的配置如下：

blacklist {

devnode "^sda"

}

defaults {

user_friendly_names no

}

multipaths {

multipath {

wwid14945540000000000a67854c6270b4359c66c272e2f356321

alias iscsi-dm0

path_grouping_policymultibus

path_checkertur

path_selector "round-robin 0"

}

multipath {

wwid14945540000000000dcca2eda91d70b81edbcfce2357f99ee

alias iscsi-dm1

path_grouping_policymultibus

path_checkertur

path_selector "round-robin 0"

}

multipath {

wwid1494554000000000020f763489c165561101813333957ed96

alias iscsi-dm2

path_grouping_policymultibus

path_checkertur

path_selector "round-robin 0"

}

multipath {

wwid14945540000000000919ca813020a195422ba3663e1f03cc3

alias iscsi-dm3

path_grouping_policymultibus

path_checkertur

path_selector "round-robin 0"

}

}

devices {

device {

vendor "iSCSI-Enterprise"

product "Virtual disk"

path_grouping_policymultibus

getuid_callout "/sbin/scsi_id -g -u -s /block/%n"

path_checkerreadsector0

path_selector "round-robin 0"

}

}

4、命令

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[root@web2 ~]# multipath -h

multipath-tools v0.4.7 (03/12, 2006)

Usage: multipath[-v level] [-d] [-h|-l|-ll|-f|-F|-r]

[-p failover|multibus|group_by_serial|group_by_prio]

[device]

-v levelverbosity level

0no output

1print created devmap names only

2default verbosity

3print debug information

-h print this usage text

-b file bindings file location

-d dry run, do not create or update devmaps

-l show multipath topology (sysfs and DM info)

-ll show multipath topology (maximum info)

-f flush a multipath device map

-F flush all multipath device maps

-r force devmap reload

-p policy force all maps to specified policy :

failover 1 path per priority group

multibus all paths in 1 priority group

group_by_serial 1 priority group per serial

group_by_prio1 priority group per priority lvl

group_by_node_name 1 priority group per target node

device limit scope to the device's multipath

(udev-style $DEVNAME reference, eg /dev/sdb

or major:minor or a device map name)

[root@web2 ~]#

5、启动关闭

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# /etc/init.d/multipathd start #开启mulitipath服务

service multipath start

service multipath restart

service multipath shutdown

6、如何获取wwid

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1、

[root@vxfs01 ~]# cat /var/lib/multipath/bindings

# Multipath bindings, Version : 1.0

# NOTE: this file is automatically maintained by the multipath program.

# You should not need to edit this file in normal circumstances.

#

# Format:

# alias wwid

#

mpath0 36006016051d50e0035744871c912de11

mpath1 36006016051d50e0034744871c912de11

mpath2 36006016051d50e0032744871c912de11

mpath3 36006016051d50e0039744871c912de11

mpath4 36006016051d50e003a744871c912de11

2、

[root@vxfs01 ~]# multipath -v3 |grep 3600

sdb: uid = 36006016051d50e003a744871c912de11 (callout)

sdc: uid = 36006016051d50e003a744871c912de11 (callout)

sdd: uid = 36006016051d50e003a744871c912de11 (callout)

sde: uid = 36006016051d50e003a744871c912de11 (callout)

36006016051d50e003a744871c912de11 1:0:0:0 sdb 8:16 0 [undef][ready] DGC,RAI

36006016051d50e003a744871c912de11 1:0:1:0 sdc 8:32 1 [undef][ready] DGC,RAI

36006016051d50e003a744871c912de11 2:0:0:0 sdd 8:48 1 [undef][ready] DGC,RAI

36006016051d50e003a744871c912de11 2:0:1:0 sde 8:64 0 [undef][ready] DGC,RAI

Found matching wwid [36006016051d50e003a744871c912de11] in bindings file.

比较详细的文字：

http://zhumeng8337797.blog.163.com/blog/static/1007689142013416111534352/

http://blog.csdn.net/wuweilong/article/details/14184097

RHEL官网资料：

http://www.prudentwoo.com/wp-content/uploads/downloads/2013/11/Red_Hat_Enterprise_Linux-5-DM_Multipath-en-US.pdf

http://www.prudentwoo.com/wp-content/uploads/downloads/2013/11/Red_Hat_Enterprise_Linux-5-DM_Multipath-zh-CN.pdf

http://www.prudentwoo.com/wp-content/uploads/downloads/2013/11/Red_Hat_Enterprise_Linux-6-DM_Multipath-en-US.pdf

http://www.prudentwoo.com/wp-content/uploads/downloads/2013/11/Red_Hat_Enterprise_Linux-6-DM_Multipath-zh-CN.pdf

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