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How database verification throttling works

Eseutil.exe, the Microsoft Exchange consistency checker utility, inserts a one-second pause after a given number of input output (I/O) operations during the database physical consistency verification. ChkSgFiles, the Microsoft Exchange integrity verification library, inserts a one-second pause after a given number of I/O operations during the database physical consistency verification.

Eseutil.exe and ChkSgFiles read 512 KB for each database checksum verification I/O operation. Therefore, when configuring the throttling value, the maximum throughput rate for database checksum verification is decreased to the following:

512 KB per I/O × x I/Os per second = 512 × x KBps

You can decrease the maximum throughput rate by decreasing the number of input output operations (x) that elapse between one-second pauses.

Number of I/O operations (x) between one-second pauses Maximum possible database verification speed
Calculation Maximum speed
100 512 KB/IO × 100 IO/sec = 51,200 KBps 50 MBps
150 512 KB/IO × 150 IO/sec = 76,800 KBps 75 MBps
200 512 KB/IO × 200 IO/sec = 102,400 KBps 100 MBps
250 512 KB/IO × 250 IO/sec = 128,000 KBps 125 MBps
Note: Decreasing the Eseutil.exe and ChkSgFiles database verification throughput causes the database checksum verification to take longer to complete. This also means that a backup job that is configured with verification also takes longer to complete. However, decreasing verification throughput does not cause a backup job without verification configured to take any longer to complete.