Increase Transfer Size; Analyze Your I/Os - HP PCIe U320 User Manual

Scsi host bus adapter

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Increase transfer size

If you are writing to an application that uses a lot of sequential disk I/O to a contiguous area on disk,

you should use as large a transfer size as possible to reduce overhead on the system, on the SCSI bus

and within disk drives.

For large sequential data transfers, use Direct I/O by selecting FILE_FLAG_WRITE_THROUGH and

FILE_FLAG_NO_BUFFERING ﬂags with your CreateFile call to avoid the overhead of copying data

from one area of memory to another, to reduce the number of SCSI commands that must be executed,

and to leave system pages available for other data.

If your application requires a small number of I/Os and the transfers are rather small, however, you may

get better performance by letting the system cache your data in the system pages.

You might want to use over-lapped I/O using the FILE_FLAG_OVERLAPPED option with the

CreateFile call. Overlapped I/O allows the application to send many commands to the device at

once.

Troubleshooting

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