今天用Dynamips做VLAN的试验使用exit命令出现：
SW1(vlan)#exit
% not enough space on flash to store vlan database. trying squeeze...First create squeeze log by erasing the entire device
% error squeezing flash - (Missing or corrupted log)
Error on database apply 40: NV storage failure
Use 'abort' command to exit
SW1(vlan)#
sw1#erase flash:
Erasing the flash filesystem will remove all files! Continue? [confirm]
Erasing device... eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee ...erased
Erase of flash: complete
的错误提示，使用apply也会出现如上的错误信息，无法创建VLAN。
解决办法:出现错误时候，输入abort先退到特权模式，然后输入erase flash，再进入vlan database配置vlan。