OpenVMS DCL Dictionary

Updated: 11 December 1998

OpenVMS DCL Dictionary

Contents

Index

SHOW MEMORY

Displays the availability and usage of those system resources that are related to memory.

Format

SHOW MEMORY

Parameters

None.

Description

The information provided by the SHOW MEMORY command can help you determine whether to change certain system memory resources to improve system performance. The system memory resources are as follows:

Physical memory
Process entry slots and balance slots
Nonpaged and paged dynamic memory
Space in paging and swapping files

When the SHOW MEMORY command is executed, a display is written to SYS$OUTPUT. Depending on which qualifiers you specify, the display shows the following memory resource statistics:

Physical memory usage
Bad page list
Number of pages allocated to an OpenVMS system
Slot usage
Dynamic memory usage (in bytes)
Paging file usage (in blocks)
Dynamic memory
Granularity hint regions for code and data (Alpha only)
Virtual I/O Cache facility (VAX only)

For a detailed description of each item displayed, see the examples.

Qualifiers

/ALL (default)
Displays all available information, that is, information displayed by the /FILES, /PHYSICAL_PAGES, /POOL, and /SLOTS qualifiers.
/BUFFER_OBJECTS (Alpha only)
Displays information about system resources used by buffer objects.
/CACHE
Displays information about the Virtual I/O Cache facility. The Cache facility information is displayed as part of the SHOW MEMORY and SHOW MEMORY/CACHE/FULL commands.
/EXACT
Use with the /PAGE=SAVE and /SEARCH qualifiers to specify a search string that must match the search string exactly and must be enclosed with quotation marks (" ").
If you specify the /EXACT qualifier without the /SEARCH qualifier, exact search mode is enabled when you set the search string with the Find (E1) key.
/FILES
Displays information about the use of each paging and swapping file currently installed.
/FULL
Displays additional information about each pool area or paging and swapping file currently installed, when used with the /POOL or the /FILES qualifier. This qualifier is ignored unless the /FILES or the /POOL qualifier is specified explicitly. When used with the /CACHE qualifier, /FULL displays additional information about the use of the Virtual I/O Cache facility.
/GH_REGIONS
On Alpha, displays information about the granularity hint regions (GHR) that have been established. For each of these regions, information is displayed about the size of the region, the amount of free memory, the amount of memory in use, and the amount of memory released to OpenVMS from the region. The granularity hint regions information is also displayed as part of SHOW MEMORY, SHOW MEMORY/ALL, and SHOW MEMORY/FULL commands.
/HIGHLIGHT[=keyword]
Use with the /PAGE=SAVE and /SEARCH qualifiers to specify the type of highlighting you want when a search string is found. When a string is found, the entire line is highlighted. You can use the following keywords: BOLD, BLINK, REVERSE, and UNDERLINE. BOLD is the default highlighting.
/OUTPUT[=filespec]

/NOOUTPUT
Controls where the output of the command is sent. If you do not enter the qualifier, or if you enter the /OUTPUT qualifier without a file specification, the output is sent to the current process default output stream or device, identified by the logical name SYS$OUTPUT.
If you enter the /OUTPUT qualifier with a partial file specification (for example, specifying only a directory), SHOW is the default file name and .LIS the default file type. If you enter a file specification, it cannot include asterisk (*) and the percent sign (%) wildcard characters.
If you enter the /NOOUTPUT qualifier, output is suppressed.
/PAGE[=keyword]

/NOPAGE (default)
Controls the display of memory information on the screen.
You can use the following keywords with the /PAGE qualifier:

CLEAR_SCREEN Clears the screen before each page is displayed.

SCROLL Displays information one line at a time.

SAVE[= n] Enables screen navigation of information, where n is the number of pages to store.

The /PAGE=SAVE qualifier allows you to navigate through screens of information. The /PAGE=SAVE qualifier stores up to 5 screens of up to 255 columns of information. When you use the /PAGE=SAVE qualifier, you can use the following keys to navigate through the information:

Key Sequence Description

Up arrow key, Ctrl/B Scroll up one line.

Down arrow key Scroll down one line.

Left arrow key Scroll left one column.

Right arrow key Scroll right one column.

Find (E1) Specify a string to find when the information is displayed.

Insert Here (E2) Scroll right one half screen.

Remove (E3) Scroll left one half screen.

Select (E4) Toggle 80/132 column mode.

Prev Screen (E5) Get the previous page of information.

Next Screen (E6), Return, Enter, Space Get the next page of information.

F10, Ctrl/Z Exit. (Some utilities define these differently.)

Help (F15) Display utility help text.

Do (F16) Toggle the display to oldest/newest page.

Ctrl/W Refresh the display.

The /PAGE qualifier is not compatible with the /OUTPUT qualifier.
/PHYSICAL_PAGES
Displays information about the amount of physical memory and the number of free and modified pages.
/POOL
Displays information about the usage of each dynamic memory (pool) area, including the amount of free space and the size of the largest contiguous block in each area.
/RESERVED (Alpha only)
Displays information about memory reservations.
/SEARCH="string"
Use with the /PAGE=SAVE qualifier to specify a string that you want to find in the information being displayed. Quotation marks are required for the /SEARCH qualifier, if you include spaces in the text string.
You can also dynamically change the search string by pressing the Find key (E1) while the information is being displayed. Quotation marks are not required for a dynamic search.
/SLOTS
Displays information about the availability of partition control block (PCB) vector slots and balance slots.
/WRAP

/NOWRAP (default)
Use with the /PAGE=SAVE qualifier to limit the number of columns to the width of the screen and to wrap lines that extend beyond the width of the screen to the next line.
The /NOWRAP qualifier extends lines beyond the width of the screen and can be seen when you use the scrolling (left and right) features provided by the /PAGE=SAVE qualifier.

Key Sequence	Description
Up arrow key, Ctrl/B	Scroll up one line.
Down arrow key	Scroll down one line.
Left arrow key	Scroll left one column.
Right arrow key	Scroll right one column.
Find (E1)	Specify a string to find when the information is displayed.
Insert Here (E2)	Scroll right one half screen.
Remove (E3)	Scroll left one half screen.
Select (E4)	Toggle 80/132 column mode.
Prev Screen (E5)	Get the previous page of information.
Next Screen (E6), Return, Enter, Space	Get the next page of information.
F10, Ctrl/Z	Exit. (Some utilities define these differently.)
Help (F15)	Display utility help text.
Do (F16)	Toggle the display to oldest/newest page.
Ctrl/W	Refresh the display.

Examples

#1
$ SHOW MEMORY System Memory Resources on 3-NOV-1998 10:14:45.68 Physical Memory Usage (pages): Total Free In Use Modified Main Memory (24.00Mb) 49152 16390 31056 1706 Virtual I/O Cache Usage (pages): Total Free In Use Maximum 9232 0 9232 18055 Slot Usage (slots): Total Free Resident Swapped Process Entry Slots 26 3 21 2 Balance Set Slots 23 1 21 1 Dynamic Memory Usage (bytes): Total Free In Use Largest Nonpaged Dynamic Memory 462336 8304 454032 4608 Paged Dynamic Memory 348672 117120 231552 114976 Paging File Usage (pages): Free Reservable Total DISK$DKA300:[SYS0.SYSEXE]PAGEFILE.SYS 46514 -3239 50000 Of the physical pages in use, 5162 pages are permanently allocated to VMS.

$ SHOW MEMORY
         
      System Memory Resources on  3-NOV-1998 10:14:45.68 
 
Physical Memory Usage (pages):   Total     Free     In Use   Modified 
  Main Memory (24.00Mb)          49152    16390      31056       1706 
 
Virtual I/O Cache Usage (pages): Total     Free     In Use    Maximum 
                                  9232        0       9232      18055 
 
Slot Usage (slots):              Total     Free   Resident    Swapped 
  Process Entry Slots               26        3         21          2 
  Balance Set Slots                 23        1         21          1 
 
Dynamic Memory Usage (bytes):    Total     Free     In Use    Largest 
  Nonpaged Dynamic Memory       462336     8304     454032       4608 
  Paged Dynamic Memory          348672   117120     231552     114976 
 
Paging File Usage (pages):                  Free   Reservable   Total 
  DISK$DKA300:[SYS0.SYSEXE]PAGEFILE.SYS    46514        -3239   50000 
 
Of the physical pages in use, 5162 pages are permanently allocated 
  to VMS.

This example shows reservable pages. Here, the reservable pages are a negative value which indicates that you may want to consider adding to the fixed amount of pagefile space available.

#2
$ SHOW MEMORY/CACHE/FULL System Memory Resources on 3-NOV-1998 18:36:12.79 Virtual I/O Cache Total Size (pages) (1) 2422 Read IO Count (6) 9577 Free Pages (2) 18 Read Hit Count (7) 5651 Pages in Use (3) 2404 Read Hit Rate (8) 59% Maximum Size (SPTEs) (4) 11432 Write IO Count (9) 2743 Files Retained (5) 99 IO Bypassing the Cache (10) 88

$ SHOW MEMORY/CACHE/FULL
            System Memory Resources on 3-NOV-1998 18:36:12.79
Virtual I/O Cache
Total Size (pages)   (1)   2422    Read IO Count          (6)     9577
Free Pages           (2)   18      Read Hit Count         (7)     5651
Pages in Use         (3)   2404    Read Hit Rate          (8)     59%
Maximum Size (SPTEs) (4)   11432   Write IO Count         (9)     2743
Files Retained       (5)   99      IO Bypassing the Cache (10)     88

Note
This example shows the output for the SHOW MEMORY/CACHE/FULL command on a VAX system. The SHOW MEMORY/CACHE/FULL command will display slightly different field on an Alpha system.

Virtual I/O Cache Usage (in Pages)
Shows the use of the Virtual I/O Cache facility on VAX.

(1) Total Size Displays the total number of system memory pages that the Virtual I/O cache currently controls.

(2) Free Pages Displays the number of pages controlled by the Virtual I/O cache that do not contain cache data.

(3) Pages in Use Displays the number of pages controlled by the Virtual I/O cache that contain valid cached data.

(4) Maximum Size Shows the maximum size that the cache could ever grow to.

(5) Files Retained Displays the number of files that are closed but the file system control information is being retained because they have valid data residing in the cache.

(6) Read I/O Count Displays the total number of read I/Os that have been seen by the Virtual I/O cache since the last system.

(7) Read Hit Count Displays the total number of read I/Os that did not do a physical I/O because the data for them was found in the cache since the last system BOOT.

(8) Read Hit Rate Displays the read hit count and read I/O count ratio.

(9) Write I/O Count Shows the total number of write I/Os that have been seen by the cache since the last system BOOT.

(10) I/O Bypassing Displays the count of I/Os that for some reason did not attempt to satisfy the request/update by the cache.

#3
$ SHOW MEMORY/PHYSICAL_PAGES System Memory Resources on 3-NOV-1998 16:11:30.76 Physical Memory Usage (pages): Total (1) Free (2) In Use (3) Modified (4) Main Memory (32.00Mb) 65536 44233 20955 308 Of the physical pages in use, 10970 pages are permanently allocated to VMS.

$ SHOW MEMORY/PHYSICAL_PAGES
              System Memory Resources on  3-NOV-1998 16:11:30.76
Physical Memory Usage (pages):  Total (1)  Free (2)   In Use (3)  Modified (4)
Main Memory (32.00Mb)           65536    44233       20955          308
 
Of the physical pages in use, 10970 pages are permanently allocated
  to VMS.

Physical Memory Usage
Shows the use of physical memory.

(1) Total Displays the number of physical memory pages available for general system use. Multiport memory pages (existing on some VAX) used for shared memory global sections, mailboxes, and common event blocks are not included in this number.

(2) Free Displays the number of pages on the free page list.

(3) In Use Displays the number of pages currently being used. This number is calculated by adding the number of pages on the free, modified, and bad lists and then subtracting that sum from the total number of available pages.

(4) Modified Displays the number of pages on the modified page list.

Bad Page List
Shows the contents of the bad page list.

Note
This display is written only when there are pages on the bad page list.

Total Displays the number of pages on the bad page list.

Dynamic Displays the number of memory errors detected after the system was booted.

I/O Errors Displays the number of errors detected during page fault handling.

Static Displays the number of memory errors detected during boot-time scan.

By default, either single-bit or double-bit errors cause the pages to be removed during the boot-time scan.

Pages Allocated to OpenVMS
Any SHOW MEMORY display that includes the physical memory display concludes with the number of pages permanently allocated to the OpenVMS system. These pages include nonpaged executive code and data, the PFN database, nonpaged dynamic memory, the interrupt stack, and the system page table.

#4
$ SHOW MEMORY/SLOTS System Memory Resources on 3-NOV-1998 16:11:35.31 Slot Usage (slots): Total (1) Free (2) Resident (3) Swapped (4) Process Entry Slots 75 28 46 1 Balance Set Slots 70 26 44 0

Slot Usage (slots)
Displays the use of process entry slots and balance set slots.

(1) Total Displays the number of process entry slots (the value of the system parameter MAXPROCESSCNT) and balance set slots (the value of the system parameter BALSETCNT) permanently allocated when the system was bootstrapped.

(2) Free Displays the number of slots currently available.

(3) Resident Displays the number of slots currently used by memory-resident processes. The number of balance set slots in use can never be any larger than the number of process entry slots in use because the SWAPPER and NULL processes have process entry slots but do not require balance set slots.

(4) Swapped Displays the number of slots used by outswapped processes. For process entry slots, this number includes all processes that have been partially outswapped. For balance set slots, this number includes those processes that have had their process bodies outswapped but have process headers that are still resident.

#5
$ SHOW MEMORY/POOL System Memory Resources on 5-DEC-1998 03:59:35.29 Dynamic Memory Usage (bytes): Total (1) Free (2) In Use (3) Largest (4) Nonpaged Dynamic Memory 24993792 23511872 1481920 23363776 Bus Addressable Memory 131072 114688 16384 114688 Paged Dynamic Memory 5799936 3530784 2269152 3530176 Lock Manager Dynamic Memory 1048576 254976 793600

$ SHOW MEMORY/POOL
              System Memory Resources on  5-DEC-1998 03:59:35.29
 
Dynamic Memory Usage (bytes):     Total (1)    Free (2) In Use (3) Largest (4)
  Nonpaged Dynamic Memory      24993792   23511872   1481920   23363776
  Bus Addressable Memory         131072     114688     16384     114688
  Paged Dynamic Memory          5799936    3530784   2269152    3530176
  Lock Manager Dynamic Memory   1048576     254976    793600

Dynamic Memory Usage (in bytes)
Shows the use of the nonpaged and paged pool areas that allocate variably sized blocks.

(1) Total Displays the total number of bytes set aside for each area.

(2) Free Displays the total amount of free space in each dynamic memory area.

(3) In Use Displays the amount of space currently allocated from each area. This number is the total size minus the number of free bytes.

(4) Largest Displays the size of the largest contiguous block in each area. For the paged pool, this number represents the largest block that can be allocated. For the nonpaged pool, an allocation request larger than this number will cause the nonpaged pool to grow (if other constraints allow growth). This attribute does not apply to the lock manager, as all items for the lock manager are the same size.

#6
$ SHOW MEMORY/FILES System Memory Resources on 3-NOV-1998 16:11:45.83 Paging File Usage (blocks): Free (2) Reservable (3) Total (4) DISK$VMS02APR1:[SYS2.SYSEXE]SWAPFILE.SYS (1) 256 256 4096 DISK$VMS02APR1:[SYS2.SYSEXE]PAGEFILE.SYS 7613 6912 8192

$ SHOW MEMORY/FILES
              System Memory Resources on  3-NOV-1998 16:11:45.83
Paging File Usage (blocks):                   Free (2) Reservable (3) Total (4)
 DISK$VMS02APR1:[SYS2.SYSEXE]SWAPFILE.SYS (1)   256           256     4096
 DISK$VMS02APR1:[SYS2.SYSEXE]PAGEFILE.SYS     7613          6912     8192

Paging File Usage (in pages)
Shows the usage of paging and swapping files.

(1) Name Displays the complete file specification of each swapping or paging file.
The names of the primary paging file, the primary swapping file (if this file exists), and the files installed by the bootstrap operation are always displayed. The names of any secondary paging or swapping files installed by the System Generation utility (SYSGEN) are displayed only if the process using the SHOW MEMORY command has read (R) access to those files. If the process cannot read the file, the name is suppressed but the usage statistics are displayed.

(2) Free Displays the number of free blocks in each paging and swapping file currently installed. Free blocks are blocks that may be physically allocated in the file.

(3) Reservable Displays the number of reservable blocks in each paging and swapping file currently installed. Reservable blocks are blocks that may be logically claimed by a process for future physical allocation. A negative value indicates that the file may be overcommitted.
Note that a negative value is not an immediate concern but indicates that the file may become overcommitted if physical memory becomes scarce.

(4) Total Displays the total size of each paging and swapping file.

When the /FULL qualifier is included on the SHOW MEMORY command for displays of pool areas or paging file usage, additional information is included in the pool or files displays.

#7
$ SHOW MEMORY/POOL/FULL System Memory Resources on 5-DEC-1998 03:59:35.29 Nonpaged Dynamic Memory (Lists + Variable) Current Size (bytes) (1) 24993792 Current Size (pagelets) (1) 48816 Initial Size (NPAGEDYN) (2) 24993792 Initial Size (pagelets) (2) 48816 Maximum Size (NPAGEVIR) (3)499998720 Maximum Size (pagelets) (3) 976560 Free Space (bytes) (4) 22230144 Space in Use (bytes) (5)2763648 Largest Variable Block (6) 19676672 Smallest Variable Block (7) 2176 Number of Free Blocks (8) 38334 Free Blocks LEQU 64 Bytes(9) 0 Free Blocks on Lookasides(16) 38330 Lookaside Space (bytes) 2537472 Bus Addressable Memory (Lists + Variable) Current Size (bytes) (1) 131072 Current Size (pagelets) (1) 256 Initial Size (NPAGEDYN) (2) 131072 Initial Size (pagelets) (2) 256 Free Space (bytes) (4) 114688 Space in Use (bytes) (5) 16384 Largest Variable Block (6) 114688 Smallest Variable Block (7) 114688 Number of Free Blocks (8) 1 Free Blocks LEQU 64 Bytes(9) 0 Free Blocks on Lookasides(16) 0 Lookaside Space (bytes) 0 Paged Dynamic Memory Current Size (PAGEDYN) (1) 5799936 Current Size (pagelets) (1) 11328 Free Space (bytes) (4) 3518288 Space in Use (bytes) (5)2281648 Largest Variable Block (6) 3517584 Smallest Variable Block (7) 16 Number of Free Blocks (8) 25 Free Blocks LEQU 64 Bytes(9) 23 Lock Manager Dynamic Memory Current Size (Mbytes) (1) 13.85 Current Size (pages) (1) 1774 Free Space (Mbytes) (4) 10.06 Hits (12) 54050 Space In Use (5) 3.79 Misses (13) 1664 Number of Empty Pages (10) 26 Expansions (14) 1792 Number of Free Packets (11) 41244 Packet Size (15) 256

$ SHOW MEMORY/POOL/FULL
              System Memory Resources on  5-DEC-1998 03:59:35.29
 
Nonpaged Dynamic Memory                   (Lists + Variable) 
 Current Size (bytes)     (1) 24993792  Current Size (pagelets)  (1)  48816
 Initial Size (NPAGEDYN)  (2) 24993792  Initial Size (pagelets)  (2)  48816
 Maximum Size (NPAGEVIR)  (3)499998720  Maximum Size (pagelets)  (3) 976560
 Free Space (bytes)       (4) 22230144  Space in Use (bytes)     (5)2763648
 Largest Variable Block   (6) 19676672  Smallest Variable Block  (7)   2176
 Number of Free Blocks    (8)    38334  Free Blocks LEQU 64 Bytes(9)      0
 Free Blocks on Lookasides(16)    38330  Lookaside Space (bytes)    2537472
Bus Addressable Memory                    (Lists + Variable) 
 Current Size (bytes)     (1)   131072  Current Size (pagelets)  (1)    256
 Initial Size (NPAGEDYN)  (2)   131072  Initial Size (pagelets)  (2)    256
 Free Space (bytes)       (4)   114688  Space in Use (bytes)     (5)  16384
 Largest Variable Block   (6)   114688  Smallest Variable Block  (7) 114688
 Number of Free Blocks    (8)        1  Free Blocks LEQU 64 Bytes(9)      0
 Free Blocks on Lookasides(16)        0  Lookaside Space (bytes)          0
Paged Dynamic Memory                                
 Current Size (PAGEDYN)   (1)  5799936  Current Size (pagelets)  (1)  11328
 Free Space (bytes)       (4)  3518288  Space in Use (bytes)     (5)2281648
 Largest Variable Block   (6)  3517584  Smallest Variable Block  (7)     16
 Number of Free Blocks    (8)       25  Free Blocks LEQU 64 Bytes(9)     23
Lock Manager Dynamic Memory                                
 Current Size (Mbytes)    (1)    13.85  Current Size (pages)     (1)   1774
 Free Space (Mbytes)      (4)    10.06  Hits                     (12)  54050
 Space In Use             (5)     3.79  Misses                   (13)   1664
 Number of Empty Pages    (10)       26  Expansions               (14)   1792
 Number of Free Packets   (11)    41244  Packet Size              (15)    256

Dynamic Memory
Shows the use of dynamic memory areas consisting of variably sized blocks.

(1) Current Size Displays the current size (in 512-byte pagelets on Alpha and in bytes and pages on VAX) of each dynamic memory area. For the lock manager display, the unit of measurement is megabytes.

(2) Initial Size Displays the initial size of nonpaged dynamic memory and the name of the system parameter (NPAGEDYN) that controls this size.

(3) Maximum Size Displays the maximum size to which nonpaged dynamic memory can grow and the name of the system parameter (NPAGEVIR) that controls this size.

(4) Free Space Displays the amount of free space in each dynamic memory area.

(5) Space in Use Displays the amount of space currently allocated from each area.

(6) Largest Block Displays the size of the largest contiguous area in each pool area.

(7) Smallest Block Displays the size of the smallest hole (free block) in each pool area.

(8) Free Blocks Displays the total number of free blocks in each pool area. The size of this number is a measure of pool fragmentation.

(9) Blocks LEQU 64 Displays the number of free blocks that are 64 bytes long or shorter. This number is another measure of pool fragmentation because while allocation of these small blocks is unlikely, they contribute to the allocation time whenever an allocation request is made.

(10) Empty Pages Displays the number of pages that do not have any packets allocated.

(11) Free Packets Displays the total number of packets not in use. This number is the sum of free packets from partially used pages and the packets of all Empty Pages.

(12) Hits Displays the total number of packet allocations.

(13) Misses Displays the total number of packet allocation requests that could not be satisfied because the number of packets requested were not available. A miss causes dynamic memory to expand by one page to satisfy the packet allocation request.

(14) Expansions Displays the total number of times that dynamic memory increased by a page to satisfy packet allocation requests.

(15) Packet Size Displays the packet size of 256 bytes, which is used by the lock manager to hold either a lock block data structure or a resource block data structure.

(16) Lookasides Free Blocks Displays the total number of memory packets that the system has preallocated and placed on 'lookaside lists'. If a packet of the correct size is on a lookaside list, it can be allocated very quickly and efficiently, however, it can not then be used as part of any other size packet. An excess of packets on the lookaside list can be a cause for the inablity to allocate other sizes.

#8
$ SHOW MEMORY/FILES/FULL System Memory Resources on 17-DEC-1998 16:11:55.49 DISK$VMS02APR1:[SYS0.SYSEXE]SWAPFILE.SYS (1) Free Blocks (2) 256 Reservable Blocks (3) 256 Total Size (blocks) (4) 4096 Paging File Number (5) 1 Swapping Usage (processes) (6) 0 Paging Usage (processes) (7) 0 This file is used exclusively for swapping. (8) DISK$VMS02APR1:[SYS0.SYSEXE]PAGEFILE.SYS (1) Free Blocks (2) 7611 Reservable Blocks (3) 6912 Total Size (blocks) (4) 8192 Paging File Number (5) 5 Swapping Usage (processes) (6) 0 Paging Usage (processes) (7) 0 This file can be used for either paging or swapping. (8)

$ SHOW MEMORY/FILES/FULL
              System Memory Resources on  17-DEC-1998 16:11:55.49
DISK$VMS02APR1:[SYS0.SYSEXE]SWAPFILE.SYS (1)
  
Free Blocks (2)               256   Reservable Blocks (3)             256
Total Size (blocks) (4)      4096   Paging File Number (5)              1
Swapping Usage (processes) (6)  0   Paging Usage (processes) (7)        0
  This file is used exclusively for swapping. (8)  
  
DISK$VMS02APR1:[SYS0.SYSEXE]PAGEFILE.SYS (1)
Free Blocks (2)              7611   Reservable Blocks (3)            6912
Total Size (blocks) (4)      8192   Paging File Number (5)              5
Swapping Usage (processes) (6)  0   Paging Usage (processes) (7)        0
  This file can be used for either paging or swapping. (8)

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CLEAR_SCREEN	Clears the screen before each page is displayed.
SCROLL	Displays information one line at a time.
SAVE[= n]	Enables screen navigation of information, where n is the number of pages to store.

(1) Total Size	Displays the total number of system memory pages that the Virtual I/O cache currently controls.
(2) Free Pages	Displays the number of pages controlled by the Virtual I/O cache that do not contain cache data.
(3) Pages in Use	Displays the number of pages controlled by the Virtual I/O cache that contain valid cached data.
(4) Maximum Size	Shows the maximum size that the cache could ever grow to.
(5) Files Retained	Displays the number of files that are closed but the file system control information is being retained because they have valid data residing in the cache.
(6) Read I/O Count	Displays the total number of read I/Os that have been seen by the Virtual I/O cache since the last system.
(7) Read Hit Count	Displays the total number of read I/Os that did not do a physical I/O because the data for them was found in the cache since the last system BOOT.
(8) Read Hit Rate	Displays the read hit count and read I/O count ratio.
(9) Write I/O Count	Shows the total number of write I/Os that have been seen by the cache since the last system BOOT.
(10) I/O Bypassing	Displays the count of I/Os that for some reason did not attempt to satisfy the request/update by the cache.

(1) Total	Displays the number of physical memory pages available for general system use. Multiport memory pages (existing on some VAX) used for shared memory global sections, mailboxes, and common event blocks are not included in this number.
(2) Free	Displays the number of pages on the free page list.
(3) In Use	Displays the number of pages currently being used. This number is calculated by adding the number of pages on the free, modified, and bad lists and then subtracting that sum from the total number of available pages.
(4) Modified	Displays the number of pages on the modified page list.

Total	Displays the number of pages on the bad page list.
Dynamic	Displays the number of memory errors detected after the system was booted.
I/O Errors	Displays the number of errors detected during page fault handling.
Static	Displays the number of memory errors detected during boot-time scan.

(1) Total	Displays the number of process entry slots (the value of the system parameter MAXPROCESSCNT) and balance set slots (the value of the system parameter BALSETCNT) permanently allocated when the system was bootstrapped.
(2) Free	Displays the number of slots currently available.
(3) Resident	Displays the number of slots currently used by memory-resident processes. The number of balance set slots in use can never be any larger than the number of process entry slots in use because the SWAPPER and NULL processes have process entry slots but do not require balance set slots.
(4) Swapped	Displays the number of slots used by outswapped processes. For process entry slots, this number includes all processes that have been partially outswapped. For balance set slots, this number includes those processes that have had their process bodies outswapped but have process headers that are still resident.

(1) Total	Displays the total number of bytes set aside for each area.
(2) Free	Displays the total amount of free space in each dynamic memory area.
(3) In Use	Displays the amount of space currently allocated from each area. This number is the total size minus the number of free bytes.
(4) Largest	Displays the size of the largest contiguous block in each area. For the paged pool, this number represents the largest block that can be allocated. For the nonpaged pool, an allocation request larger than this number will cause the nonpaged pool to grow (if other constraints allow growth). This attribute does not apply to the lock manager, as all items for the lock manager are the same size.

(1) Name	Displays the complete file specification of each swapping or paging file. The names of the primary paging file, the primary swapping file (if this file exists), and the files installed by the bootstrap operation are always displayed. The names of any secondary paging or swapping files installed by the System Generation utility (SYSGEN) are displayed only if the process using the SHOW MEMORY command has read (R) access to those files. If the process cannot read the file, the name is suppressed but the usage statistics are displayed.
(2) Free	Displays the number of free blocks in each paging and swapping file currently installed. Free blocks are blocks that may be physically allocated in the file.
(3) Reservable	Displays the number of reservable blocks in each paging and swapping file currently installed. Reservable blocks are blocks that may be logically claimed by a process for future physical allocation. A negative value indicates that the file may be overcommitted. Note that a negative value is not an immediate concern but indicates that the file may become overcommitted if physical memory becomes scarce.
(4) Total	Displays the total size of each paging and swapping file.

(1) Current Size	Displays the current size (in 512-byte pagelets on Alpha and in bytes and pages on VAX) of each dynamic memory area. For the lock manager display, the unit of measurement is megabytes.
(2) Initial Size	Displays the initial size of nonpaged dynamic memory and the name of the system parameter (NPAGEDYN) that controls this size.
(3) Maximum Size	Displays the maximum size to which nonpaged dynamic memory can grow and the name of the system parameter (NPAGEVIR) that controls this size.
(4) Free Space	Displays the amount of free space in each dynamic memory area.
(5) Space in Use	Displays the amount of space currently allocated from each area.
(6) Largest Block	Displays the size of the largest contiguous area in each pool area.
(7) Smallest Block	Displays the size of the smallest hole (free block) in each pool area.
(8) Free Blocks	Displays the total number of free blocks in each pool area. The size of this number is a measure of pool fragmentation.
(9) Blocks LEQU 64	Displays the number of free blocks that are 64 bytes long or shorter. This number is another measure of pool fragmentation because while allocation of these small blocks is unlikely, they contribute to the allocation time whenever an allocation request is made.
(10) Empty Pages	Displays the number of pages that do not have any packets allocated.
(11) Free Packets	Displays the total number of packets not in use. This number is the sum of free packets from partially used pages and the packets of all Empty Pages.
(12) Hits	Displays the total number of packet allocations.
(13) Misses	Displays the total number of packet allocation requests that could not be satisfied because the number of packets requested were not available. A miss causes dynamic memory to expand by one page to satisfy the packet allocation request.
(14) Expansions	Displays the total number of times that dynamic memory increased by a page to satisfy packet allocation requests.
(15) Packet Size	Displays the packet size of 256 bytes, which is used by the lock manager to hold either a lock block data structure or a resource block data structure.
(16) Lookasides Free Blocks	Displays the total number of memory packets that the system has preallocated and placed on 'lookaside lists'. If a packet of the correct size is on a lookaside list, it can be allocated very quickly and efficiently, however, it can not then be used as part of any other size packet. An excess of packets on the lookaside list can be a cause for the inablity to allocate other sizes.