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14 BP1062 | Best Practices for Decision Support Systems with Microsoft SQL Server 2012 using Dell EqualLogic PS Series
Storage Arrays
interface is 1280 MB/sec. From the tests conducted, the maximum average read throughput achieved was
1042 MB/sec for a 128K block size and maximum average write throughput achieved was 680 MB/sec for
256K block size.
IOMeter sequential I/O throughput Figure 3
Figure 4 shows the maximum random read throughput obtained for different I/O block sizes. The read
throughput increased as the block sizes increased from 64K to 1MB.
IOMeter random read throughput Figure 4
Note: By default, the MaxTransferLength (maximum data size of an I/O request) in the Windows iSCSI
initiator is 256K. I/Os larger than 256K are split into 256K chunks. Because the MaxTransferLength
setting was left at the default for the tests in section 5, the block sizes 512K and 1MB were broken into
256K blocks. For details, refer to the section titled, ”Microsoft Software Initiator Kernel Mode Driver” in
the iSCSI initiator Users Guide for Windows 7 and Windows Server 2008 R2 at
http://www.microsoft.com/en-us/download/details.aspx?id=6408
1030
1042
1030
1022
1016
368
663
680
607
571
0
200
400
600
800
1000
1200
64K 128K 256K 512K 1MB
Throughput (MB/sec)
I/O block size
100% sequential I/O throughput
Read Throughput
Write Throughput
262
342
396
402
436
0
100
200
300
400
500
64K 128K 256K 512K 1MB
Throughput (MB/sec)
I/O block size
100% random read throughput
Read Throughput