r620服务器中，比较经常出现idrac无法连接，或者连接用户数超限的问题，有几个方法可以尝试下：
1、 升级idrac卡的firmware
下载并升级最新的1.57.57版本的firmware：?driverid=xh6fx
该版本的bug fix中提到过一点：
– fix for issues that cause idrac7 sluggish responsiveness after a prolonged period of time (approx. 45-100 days, depending on the usage). in some cases, if the idrac is not reset, the idrac may become unresponsive and requires a server ac power on reset. this issue was introduced in firmware release 1.50.50 and fixed in 1.56.55.
该版本解决了idrac启动45-100天后可能出现无法响应的问题。
2、 杀掉超时连接会话
有2个方法：
a. 重启bmc卡
执行命令： ipmitool mc reset cold 即可，将bmc卡重启后，所有的session都会重置释放。
b. 杀掉超时会话
前提是，允许bmc卡通过网络远程连接
ipmitool lan set 1 access on
或者在下面这个地方启用
idrac 设置 => 服务 => vnc 服务器 => 超时
或者在idrac卡的下面这个地方设置：
idrac 设置 => 网络 => ipmi 设置 => 启用 lan 上的 ipmi
同时，建议把web server及ssh服务的timeout值适当调低：
idrac 设置 => 服务 => web server => 超时
idrac 设置 => 服务 => ssh => 超时
idrac 设置 => 服务 => telnet => 超时
idrac 设置 => 服务 => vnc 服务器 => 超时
利用 racadm 工具（racadm工具的安装自行搞定）关闭超时会话，首先可以查看当前的会话连接情况，例如：
[ 15:41:10-root@fzdm-10-59-xx-xx:~ ]#racadm -r 10.59.xx.xx -uroot -p”xx” getssninfo
security alert: certificate is invalid – self signed certificate
continuing execution. use -s option for racadm to stop execution on certificate-related errors.
ssnid type user ip address login date/time
—————————————————————————
20 ssh root 10.5.xx.xx 11/18/2014 15:38:43
25 gui root 10.5.xx.xx 11/18/2014 15:40:27
28 racadm root 10.59.xx.xx 11/18/2014 15:41:17
29 ssh root 10.59.xx.xx 11/18/2014 15:41:18
再执行下面的命令，关闭超时会话连接
[ 15:40:52-root@fzdm-10-59-xx-xx:~ ]#racadm -r 10.59.xx.xx -uroot -p”xx” closessn -i 25
security alert: certificate is invalid – self signed certificate
continuing execution. use -s option for racadm to stop execution on certificate-related errors.
session 19 closed successfully.