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