I/O

The I/O window shows information about the I/O activity.

Physical I/O (pages per second)

Page reads/s Number of physical database page reads that are issued per second. This statistic displays the total number of physical page reads across all databases. Because physical I/O is expensive, you may be able to minimize the cost, either by using a larger data cache, intelligent indexes, and more efficient queries, or by changing the database design.
Page writes/s Number of physical database page writes issued.
Readahead Number of pages read in anticipation of use.
Lazy writes Number of buffers written per second by the buffer manager's lazy writer. The lazy writer is a system process that flushes out batches of dirty, aged buffers (buffers that contain changes that must be written back to disk before the buffer can be reused for a different page) and make them available to user processes. The lazy writer eliminates the need to perform frequent checkpoints in order to create available buffers.
Checkpoint Number of pages flushed to disk per second by a checkpoint or other operation that require all dirty pages to be flushed.

Logical Reads (Pages per second)

Number of requests to find a page in the buffer pool.

Data Access Methods (rates per second)

Page Splits Number of page splits per second that occur as the result of overflowing index pages.
Pages Allocations Number of pages allocated per second to database objects used for storing index or data records.
Page Deallocations Number of pages deallocated per second from database objects used for storing index or data records.
FreeSpace Scans Number of scans per second that were initiated to search for free space in which to insert a new record fragment.
Forwarded Records Number of records per second fetched through forwarded record pointers.
Skipped Ghosted Records Number of ghosted records per second skipped during scans.
Table Lock Escalations Number of times locks on a table were escalated.

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