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Figure 26 – Win2K SCSI and IDE unbuffered throughput
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| bet | 37/47 | | Sana | 30.03.2021 | | Hajmi | 1,33 Mb. | | #13789 |
Figure 26 – Win2K SCSI and IDE unbuffered throughput. Like its buffered throughput, the Fireball’s unbuffered throughput was very good. The trend lines of the Fireball IDE drive, connected to the motherboard IDE controller with DMA, were similar to that of the Atlas 10K SCSI drives with two-deep as the optimal depth of reads, providing disk speed at all request sizes. A depth of one was optimal for writes, providing disk speed at 8KB and larger requests. When the Fireball was attached to the 3ware card, small 2KB reads suffered. The 3ware card wasn’t handling as many IOs per second as the motherboard IDE channel.
Figure 27 shows both SCSI and IDE unbuffered overheads. Only overhead for an IDE drive connected to the 3ware card is shown, as unbuffered overhead for an IDE drive connected to the motherboard controller had almost identical results. Unbuffered overhead for the 3ware card was slightly higher than that of SCSI per request. Each IDE request had a fixed cost of 57s. The marginal cost was .42s per KB written and .53s per KB read. This compares to a fixed cost of 32s and a marginal cost of .25s per KB for SCSI.
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Figure 27 – Win2K SCSI and IDE unbuffered overheads. As shown above, overhead between SCSI and IDE is very similar. Overhead for the 3ware card was slightly higher than that of the Adaptec SCSI controller.
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