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Cache Object
The Cache performance object consists of counters that monitor the file system
cache, an area of physical memory that stores recently used data as long as
possible to permit access to the data without having to read from the disk.
Because applications typically use the cache, the cache is monitored as an indicator
of application I/O operations. When memory is plentiful, the cache can grow,
but when memory is scarce, the cache can become too small to be effective.
Data Maps/sec
Data Maps/sec is the frequency that a file system such as NTFS, maps a page of
a file into the file system cache to read the page.
Detail Level: Expert
Counter Type: PERF_COUNTER_COUNTER
Sync Data Maps/sec
Sync Data Maps/sec counts the frequency that a file system, such as NTFS, maps
a page of a file into the file system cache to read the page, and wishes to
wait for the page to be retrieved if it is not in main memory.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Async Data Maps/sec
Async Data Maps/sec is the frequency that an application using a file system,
such as NTFS, to map a page of a file into the file system cache to read the
page, and does not wait for the page to be retrieved if it is not in main memory.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Data Map Hits %
Data Map Hits is the percentage of data maps in the file system cache that
could be resolved without having to retrieve a page from the disk, because the
page was already in physical memory.
Detail Level: Wizard
Counter Type: PERF_SAMPLE_FRACTION
Data Map Hits %
Data Map Hits is the percentage of data maps in the file system cache that
could be resolved without having to retrieve a page from the disk, because the
page was already in physical memory.
Detail Level: Wizard
Counter Type: PERF_SAMPLE_BASE
Data Map Pins/sec
Data Map Pins/sec is the frequency of data maps in the file system cache that
resulted in pinning a page in main memory, an action usually preparatory to
writing to the file on disk. While pinned, a page's physical address in main
memory and virtual address in the file system cache will not be altered.
Detail Level: Wizard
Counter Type: PERF_SAMPLE_FRACTION
Data Map Pins/sec
Data Map Pins/sec is the frequency of data maps in the file system cache that
resulted in pinning a page in main memory, an action usually preparatory to
writing to the file on disk. While pinned, a page's physical address in main
memory and virtual address in the file system cache will not be altered.
Detail Level: Wizard
Counter Type: PERF_SAMPLE_BASE
Pin Reads/sec
Pin Reads/sec is the frequency of reading data into the file system cache
preparatory to writing the data back to disk. Pages read in this fashion are pinned
in memory at the completion of the read. While pinned, a page's physical
address in the file system cache will not be altered.
Detail Level: Expert
Counter Type: PERF_COUNTER_COUNTER
Sync Pin Reads/sec
Sync Pin Reads/sec is the frequency of reading data into the file system cache
preparatory to writing the data back to disk. Pages read in this fashion are
pinned in memory at the completion of the read. The file system will not regain
control until the page is pinned in the file system cache, in particular if the
disk must be accessed to retrieve the page. While pinned, a page's physical
address in the file system cache will not be altered.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Async Pin Reads/sec
Async Pin Reads/sec is the frequency of reading data into the file system
cache preparatory to writing the data back to disk. Pages read in this fashion are
pinned in memory at the completion of the read. The file system will regain
control immediately even if the disk must be accessed to retrieve the page. While
pinned, a page's physical address will not be altered.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Pin Read Hits %
Pin Read Hits is the percentage of pin read requests that hit the file system
cache, i.e., did not require a disk read in order to provide access to the page
in the file system cache. While pinned, a page's physical address in the file
system cache will not be altered. The LAN Redirector uses this method for
retrieving data from the cache, as does the LAN Server for small transfers. This is
usually the method used by the disk file systems as well.
Detail Level: Expert
Counter Type: PERF_SAMPLE_FRACTION
Pin Read Hits %
Pin Read Hits is the percentage of pin read requests that hit the file system
cache, i.e., did not require a disk read in order to provide access to the page
in the file system cache. While pinned, a page's physical address in the file
system cache will not be altered. The LAN Redirector uses this method for
retrieving data from the cache, as does the LAN Server for small transfers. This is
usually the method used by the disk file systems as well.
Detail Level: Expert
Counter Type: PERF_SAMPLE_BASE
Copy Reads/sec
Copy Reads/sec is the frequency of reads from pages of the file system cache
that involve a memory copy of the data from the cache to the application's
buffer. The LAN Redirector uses this method for retrieving information from the file
system cache, as does the LAN Server for small transfers. This is a method
used by the disk file systems as well.
Detail Level: Expert
Counter Type: PERF_COUNTER_COUNTER
Sync Copy Reads/sec
Sync Copy Reads/sec is the frequency of reads from pages of the file system
cache that involve a memory copy of the data from the cache to the application's
buffer. The file system will not regain control until the copy operation is
complete, even if the disk must be accessed to retrieve the page.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Async Copy Reads/sec
Async Copy Reads/sec is the frequency of reads from pages of the file system
cache that involve a memory copy of the data from the cache to the application's
buffer. The application will regain control immediately even if the disk must
be accessed to retrieve the page.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Copy Read Hits %
Copy Read Hits is the percentage of cache copy read requests that hit the
cache, that is, they did not require a disk read in order to provide access to the
page in the cache. A copy read is a file read operation that is satisfied by a
memory copy from a page in the cache to the application's buffer. The LAN
Redirector uses this method for retrieving information from the cache, as does the
LAN Server for small transfers. This is a method used by the disk file systems
as well.
Detail Level: Expert
Counter Type: PERF_SAMPLE_FRACTION
Copy Read Hits %
Copy Read Hits is the percentage of cache copy read requests that hit the
cache, that is, they did not require a disk read in order to provide access to the
page in the cache. A copy read is a file read operation that is satisfied by a
memory copy from a page in the cache to the application's buffer. The LAN
Redirector uses this method for retrieving information from the cache, as does the
LAN Server for small transfers. This is a method used by the disk file systems
as well.
Detail Level: Expert
Counter Type: PERF_SAMPLE_BASE
MDL Reads/sec
MDL Reads/sec is the frequency of reads from the file system cache that use a
Memory Descriptor List (MDL) to access the data. The MDL contains the physical
address of each page involved in the transfer, and thus can employ a hardware
Direct Memory Access (DMA) device to effect the copy. The LAN Server uses this
method for large transfers out of the server.
Detail Level: Expert
Counter Type: PERF_COUNTER_COUNTER
Sync MDL Reads/sec
Sync MDL Reads/sec is the frequency of reads from the file system cache that
use a Memory Descriptor List (MDL) to access the pages. The MDL contains the
physical address of each page in the transfer, thus permitting Direct Memory
Access (DMA) of the pages. If the accessed page(s) are not in main memory, the
caller will wait for the pages to fault in from the disk.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Async MDL Reads/sec
Async MDL Reads/sec is the frequency of reads from the file system cache that
use a Memory Descriptor List (MDL) to access the pages. The MDL contains the
physical address of each page in the transfer, thus permitting Direct Memory
Access (DMA) of the pages. If the accessed page(s) are not in main memory, the
calling application program will not wait for the pages to fault in from disk.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
MDL Read Hits %
MDL Read Hits is the percentage of Memory Descriptor List (MDL) read requests
to the file system cache that hit the cache, i.e., did not require disk
accesses in order to provide memory access to the page(s) in the cache.
Detail Level: Expert
Counter Type: PERF_SAMPLE_FRACTION
MDL Read Hits %
MDL Read Hits is the percentage of Memory Descriptor List (MDL) read requests
to the file system cache that hit the cache, i.e., did not require disk
accesses in order to provide memory access to the page(s) in the cache.
Detail Level: Expert
Counter Type: PERF_SAMPLE_BASE
Read Aheads/sec
Read Aheads/sec is the frequency of reads from the file system cache in which
the cache detects sequential access to a file. The read aheads permit the data
to be transferred in larger blocks than those being requested by the
application, reducing the overhead per access.
Detail Level: Advanced
Counter Type: PERF_COUNTER_COUNTER
Fast Reads/sec
Fast Reads/sec is the frequency of reads from the file system cache that
bypass the installed file system and retrieve the data directly from the cache.
Normally, file I/O requests invoke the appropriate file system to retrieve data
from a file, but this path permits direct retrieval of data from the cache without
file system involvement if the data is in the cache. Even if the data is not
in the cache, one invocation of the file system is avoided.
Detail Level: Expert
Counter Type: PERF_COUNTER_COUNTER
Sync Fast Reads/sec
Sync Fast Reads/sec is the frequency of reads from the file system cache that
bypass the installed file system and retrieve the data directly from the cache.
Normally, file I/O requests invoke the appropriate file system to retrieve
data from a file, but this path permits direct retrieval of data from the cache
without file system involvement if the data is in the cache. Even if the data is
not in the cache, one invocation of the file system is avoided. If the data is
not in the cache, the request (application program call) will wait until the
data has been retrieved from disk.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Async Fast Reads/sec
Async Fast Reads/sec is the frequency of reads from the file system cache that
bypass the installed file system and retrieve the data directly from the
cache. Normally, file I/O requests will invoke the appropriate file system to
retrieve data from a file, but this path permits data to be retrieved from the cache
directly (without file system involvement) if the data is in the cache. Even if
the data is not in the cache, one invocation of the file system is avoided. If
the data is not in the cache, the request (application program call) will not
wait until the data has been retrieved from disk, but will get control
immediately.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Fast Read Resource Misses/sec
Fast Read Resource Misses/sec is the frequency of cache misses necessitated by
the lack of available resources to satisfy the request.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Fast Read Not Possibles/sec
Fast Read Not Possibles/sec is the frequency of attempts by an Application
Program Interface (API) function call to bypass the file system to get to data in
the file system cache that could not be honored without invoking the file
system.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Lazy Write Flushes/sec
Lazy Write Flushes/sec is the rate at which the Lazy Writer thread has written
to disk. Lazy Writing is the process of updating the disk after the page has
been changed in memory, so that the application that changed the file does not
have to wait for the disk write to be complete before proceeding. More than one
page can be transferred by each write operation.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Lazy Write Pages/sec
Lazy Write Pages/sec is the rate at which the Lazy Writer thread has written
to disk. Lazy Writing is the process of updating the disk after the page has
been changed in memory, so that the application that changed the file does not
have to wait for the disk write to be complete before proceeding. More than one
page can be transferred on a single disk write operation.
Detail Level: Advanced
Counter Type: PERF_COUNTER_COUNTER
Data Flushes/sec
Data Flushes/sec is the rate at which the file system cache has flushed its
contents to disk as the result of a request to flush or to satisfy a
write-through file write request. More than one page can be transferred on each flush
operation.
Detail Level: Wizard
Counter Type: PERF_COUNTER_COUNTER
Data Flush Pages/sec
Data Flush Pages/sec is the number of pages the file system cache has flushed
to disk as a result of a request to flush or to satisfy a write-through file
write request. More than one page can be transferred on each flush operation.
Detail Level: Advanced
Counter Type: PERF_COUNTER_COUNTER
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