3Ware TwinStor Информационный листок - Страница 7

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Figure 4 shows the comparison between a pair of SCSI drives mirrored in a popular controller with a standard RAID 1

configuration and a pair of ATA drives with TwinStor in an Escalade RAID card. In this comparison, the price advantage over

SCSI is even more dramatic. The streaming performance is 73% better, because RAID 1 cannot take advantage of the

second drive to improve streaming rates. Random read rates are about the same, even though the SCSI drives used for this

test have much faster seek rates than the ATA drives used. The superlinear performance gain obtained from the adaptive

random optimization completely makes up for the difference in the drive performance.

Comparison with other classes of SCSI drives shows similar advantages for 3ware'sTwinStor technology. For instance,

twinned ATA drives compared to a single high-end, 10,000-RPM SCSI drive shows similar overall performance and much

better streaming read performance at a much lower cost.

Figure 5 shows a four-drive SCSI RAID 5 system (populated with 9.1 GB drives) using an Adaptec RAID controller compared

to two TwinStor pair of 18.2 GB ATA drives and the 3ware Escalade card. Each TwinStor pair appears as a single 18.2 GB

volume to the NT file system and the two volumes are combined into a single volume with NT software striping. Again, all

results favor the TwinStor solution. Capacity is greater because the four-drive RAID 5 solution gives a usable capacity of

three times the 9.1 GB drives, while 3ware's TwinStor solution gives twice the capacity of the 18.2 GB drives. Because of the

large penalty for writes in RAID 5, the write rates are greatly improved with the TwinStor solution. The WinBench 99 result

shows that the overal performance of TwinStor far exceeds the RAID 5 solution and delivers higher capacity with a lower

cost.

Figure 4. RAID 1 to TwinStor Comparison

Figure 5. RAID 5 to TwinStor Comparison