AIX Statistics



CPU (%)
        User User time. This indicates the amount of time a program is in user mode. Programs can run in either user mode or system mode. In user mode, the program does not require the resources of the kernel to manage memory, set variables, or perform computations.
A CPU bottleneck could occur if 'User' and 'System' combined together add up to approximately 80 percent or more.
        System System time indicates the amount of time a program is in system mode; that is, processes using kernel processes (kprocs) and others that are using kernel resources. Processes requiring the use of kernel services must switch to service mode to gain access to the services, such as to open a file or read/write data.
A CPU bottleneck could occur if 'User' and 'System' combined together add up to approximately 80 percent or more.
        Wait CPU wait. CPU idle time during which the system had at least one outstanding I/O to disk (whether local or remote) and asynchronous I/O was not in use. An I/O causes the process to block (or sleep) until the I/O is complete. Upon completion, it is placed on the run queue. A 'Wait' of over 25 percent could indicate a need to investigate the disk I/O subsystem for ways to improve throughput, such as load balancing.
        Idle CPU idle time. This indicates the percentage of time the CPU is idle without pending I/O. When the CPU is idle, it has nothing on the run queue. When there is a high aggregate value for 'Idle', it means there was nothing for the CPU to do and there were no pending I/Os. A process called wait is bound to every CPU on the system. When the CPU is idle, and there are no local I/Os pending, any pending I/O to a Network File System (NFS) is charged to 'Idle'.
Memory (4 Kb pages)
        Active Active Virtual Memory indicates the number of virtual pages accessed. This is not an indication of available memory.
        Free list This indicates the size of the free list. A large portion of real memory is utilized as a cache for file system data. It is not unusual for the size of the free list to remain small. The VMM maintains this free list. The free list entries point to buffers of 4 K pages that are readily available when required. The minimum number of pages is defined by minfree. The default value is 120. If the number of the free list drops below that defined by minfree, then the VMM steals pages until maxfree+8 is reached. Terminating applications release their memory, and those frames are added back to the free list. Persistent pages (files) are not added back to the free list. They remain in memory until the VMM steals their pages. Persistent pages are also freed when their corresponding file is deleted. A small value of fre could cause the system to start thrashing due to overcommitted memory. This does not indicate the amount of unused memory.
Paging (Unit/s)
        Reclaims The number of reclaims per second. During a page fault, when the page is on the free list and has not been reassigned, this is considered a reclaim because no new I/O request has been initiated. It also includes the pages last requested by the VMM for which I/O has not been completed or those prefetched by VMM’s read-ahead mechanism but hidden from the faulting segment.
        Pages in Indicates the number of page in requests. Those are pages that have been paged to paging space and are paged into memory when required by way of a page fault. Normally you would not want to see more than five sustained pages per second (as a rule of thumb) reported as paging effects performance. A system that is paging data in from paging space results in slower performance because the CPU has to wait for data before processing the thread. A high value of 'Pages in' may indicate a shortage of memory or indicate a need for performance tuning.
        Pages out The number of pages out process. The number of pages per second that is moved to paging space. These pages are paged out to paging space by the VMM when more memory is required. They will stay in paging space and be paged in if required. A terminating process will disclaim its pages held in paging space, and pages will also be freed when the process gives up the CPU (is preempted). 'Pages out' does not necessarily indicate thrashing, but if you are experiencing high 'Pages out' then it may be necessary to investigate the application vmo command parameters minfree and max free, and the environmental variable PSALLOC.
        Pages freed Number of pages freed. When the VMM requires memory, VMM’s page-replacement algorithm is employed to scan the Page Frame Table (PFT) to determine which pages to steal. If a page has not been referenced since the last scan, it can be stolen. If there has been no I/O for that page then the page can be stolen without being written to disk, thus minimizing the effect on performance.
        Pages scanned Represents pages scanned by the page-replacement algorithm. When page stealing occurs (when 'Free list' goes below minfree of vmo), the pages in memory are scanned to determine which can be stolen.
        Algo. Cycles This refers to the page replacement algorithm. The value refers to the number of times the page replacement algorithm does a complete cycle through memory looking for pages to steal. If this value is greater than zero, this means severe memory shortages.
Faults (Unit/s)
        Device intr. Number of device or hardware interrupts per second. An example of an interrupt would be the 10 ms clock interrupt or a disk I/O completion. Due to the clock interrupt, the minimum value you see is 100.
        System calls Number of system calls per second. These are resources provided by the kernel for the user processes and data exchange between the process and the kernel. This reported value can vary depending on workloads and on how the application is written, so it is not possible to determine a value for this. Any value of 10,000 and more should be investigated.
        Ctxt switches Kernel thread context switches per second. A CPU’s resource is divided into 10 ms time slices and a thread will run for the full 10 ms or until it gives up the CPU (is preempted). When another thread gets control of the CPU, the previous thread’s contexts and working environments must be saved and the new thread’s contexts and working environment must be restored. Any significant increase in context switches should be investigated.
Kernel Threads
        On run queue Average number of threads on the run queues per second. These threads are only waiting for CPU time and are ready to run. Each thread has a priority ranging from zero to 127. Each CPU has a run queue for each priority; therefore there are 128 run queues for each CPU. Threads are placed on the appropriate run queue. This value is computed across all run queues and all CPUs. The maximum you should see this value increase to is based on the following formula: 5 x (Nproc - Nbind), where Nproc is the number of active processors and Nbind is the number of active processors bound to processes with the bindprocessor command.
        On block queue Average number of threads on block queue per second. These threads are waiting for resource or I/O. Threads are also located in the wait queue when scheduled, but are waiting for one of their threads pages to be paged in. On an SMP system there will always be one thread on the block queue. If compressed file systems are used, then there will be an additional thread on the block queue.


        %CPU The percentage of time the process has used the CPU since the process started. The value is computed by dividing the time the process uses the CPU by the elapsed time of the process. In a multi-processor environment, the value is further divided by the number of available CPUs since several threads in the same porcess can run on different CPUs at the same time. (Because the time base over which this data is computed varies, the sum of all %CPU fields can exceed 100%.)
Memory (MB)
        VSZ Indicates, as a decimal integer, the size in megabytes of the process in virtual memory.


CPU Utilization
        User Reports the percentage of time the cpu or cpus spent in execution at the user (or application) level.
        System Reports the percentage of time the cpu or cpus spent in execution at the system (or kernel) level.
        Wait Reports the percentage of time the cpu or cpus were idle waiting for disk I/O to complete. For system-wide statistics, this value may be slightly inflated if several processors are idling at the same time, an unusual occurence.
        Idle Reports the percentage of time the cpu or cpus were idle with no outstanding disk I/O requests.
File Access system Routines
        iget/s Calls to any of several i-node lookup routines that support multiple file system types. The iget routines return a pointer to the i-node structure of a file or device.
        lookuppn/s Calls to the directory search routine that finds the address of a v-node given a path name.
        dirblk/s Number of 512-byte blocks read by the directory search routine to locate a directory entry for a specific file.
System Calls
        fork/s Reports the total number of fork system calls.
        exec/s Reports the total number of exec system calls.
Context Switches
        cswch/s Reports the number of context switches per second.

Disks IO

KB Read/Written per second
        Total Indicates the amount of data transferred (read or written) to the drive in KB per second.
        Read KB read per second.
KB read and KB written combined should not exceed 70 percent of the disk or adapter’s throughput to avoid saturation.
        Written KB written per second.
KB read and KB written combined should not exceed 70 percent of the disk or adapter’s throughput to avoid saturation.
I/O requests per second
        Req/s Indicates the number of transfers per second that were issued to the physical disk. A transfer is an I/O request at the device driver level to the physical disk. As physical I/O (read or write, to or from the disk) is expensive in terms of performance, in order to reduce the amount of physical I/O to the disk(s), multiple logical requests (reads and writes from the application) can be combined into a single physical I/O. A transfer is of an indeterminate size.
% Active Time
        % active Indicates the percentage of time the physical disk was active (bandwidth utilization for the drive). The % active figure shows the percentage of time the volume was active. This is the primary indicator of a bottleneck. Any % active over 70 percent may be considered a potential bottleneck. A drive is active during data transfer and command processing, such as seeking to a new location. The disk-use percentage is directly proportional to resource contention and inversely proportional to performance. As disk use increases, performance decreases and the time it takes for the system to respond to user requests increases. In general, when a disk’s use (% active) exceeds 70 percent, processes may be waiting longer than necessary for I/O to complete because most UNIX processes block (or sleep) while waiting for their I/O requests to complete.
        ESTABLISHED Connection has been established.
        TIME_WAIT Wait after close for remote shutdown retransmission.
        CLOSE_WAIT Remote shutdown; waiting for the socket to close.
        SYN_RECEIVED Initial synchronization of the connection under way.
        SYN_SENT Actively trying to establish connection.
Packets per second
        Input Packets received on the network interface per second.
        Output Packets sent to the interface per second.
Errors per second
        Input Receive errors on this network interface per second.
        Output Transmit errors on the interface per second.
        Collisions The number of collisions on the interface. The collision count for Ethernet interfaces is not supported.


Usage History (MB)

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