单项选择题 After completing an installation of new software， a system administrator notices the system is slow.  To troubleshoot the performance， which single AIX command could be used to provide a real-time display of CPU， memory and disk utilization（）

单项选择题 A System p administrator is attempting to restore some files from a backup tape. The restore failed. The system administrator suspects the block size of the tape drive is incorrect.  Which of the following commands can be used to determine the block size of the backup tape （）

单项选择题 During system boot， the boot process hangs at LED 0551.  Which of the following is a likely cause（）