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Figure 11 – Win2K single disk random IOs per second
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| bet | 20/47 | | Sana | 30.03.2021 | | Hajmi | 1,33 Mb. | | #13789 |
Figure 11 – Win2K single disk random IOs per second. The Quantum Atlas 10K drives showed good unbuffered random IO performance. When FS buffering is used, there is a significant 66% improvement in the read IO/s rate (compared to the one-deep rate), but the write IO/s suffers from the additional read. Win2K sorts requests to optimize disk arm movement. These measurements were all taken with WCE.
Figure 12 shows that processor cost per MB for 8KB buffered random requests is about 20ms for reads and 35ms for writes. For random writes, the additional cost of the additional read for each write is reflected by the write overhead being almost double that of the read overhead.
Unbuffered random requests cost much less than their buffered counterparts. Unbuffered requests averaged slightly over 9ms per MB on both writes and reads. This cost is similar for 2, 3, and 4 disk configurations.
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Figure 12 – Buffered and unbuffered random IO overhead. Random IO overhead for unbuffered requests remains low for random unbuffered requests. Buffered random requests are more than twice as expensive than unbuffered requests for reads, and over four times as expensive for writes. The additional read that each buffered random write generates causes the cost of doing random buffered writes.
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