Databases Reference
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Extract the throughput in MB/Sec, and note the latency and IOPS (and relevant block size) at which the
maximum values were obtained. Now that you have a set of four values (MB/Sec for R-R. R-W, S-R, S-W)
that represent the maximum throughput of each test configuration, you can much more easily compare
different systems than when you are looking at either a lot of lines plotted on charts or large tables
of numbers.
Here is a table of real-life test results from a number of different storage subsystems. Using this approach
it is easy to identify the storage with the best throughput.
Table 12-10: SQLIO Summary Results from Different Storage Subsystems
System
Random Write
Random Read
Sequential Read
Sequential Write
A
96MB/s at 1MB
23MB/s at 256KB
110MB/s at 1MB
100MB/s at 1MB
B
101MB/s at 1MB
24MB/s at 256KB
114MB/s at 1MB
104MB/s at 1MB
C
38MB/s at 256KB
12MB/s at 128KB
126MB/s at 1MB
35MB/s at 256KB
D
14MB/s at 128KB
3MB/s at 32KB
96MB/s at 512KB
16MB/s at 128KB
E
26MB/s at 256KB
17MB/s at 128KB
118MB/s at 1MB
31MB/s at 256KB
F
96MB/s at 1MB
193MB/s at 2MB
195MB/s at 2MB
159MB/s at 1MB
All the results in the table are MB/Sec at max latency of 10 mSec. These results are from running test E,
which varies the block size. The block size is given for each result. Here is a further breakdown:
❑
System A is a desktop system with a four-port SATA adapter on a PCI bus. The four disks are
configured as a single RAID 0 stripe set using a 32 K stripe size. This adapter has a 64MB cache
that is not configurable.
❑
System B is the same as system A with the exception that this time the array is configured using
a 128KB stripe size.
❑
System C is a rack mounted server system with 4
73 GB SCSI disks, using a caching RAID
controller. The cache on the controller is believed to be 128MB. The four disks are configured
into a RAID 0 array with an 8 KB stripe size.
×
❑
System D, same as system C but using RAID 5 with 8KB stripe.
❑
System E, same as system C but using RAID 10 and an 8KB stripe.
❑
System F is another rack mounted server, this time connected to an Enterprise class SAN sys-
tem with 120
×
10 K rpm SCSI disks. The SAN has 64 GB cache, and is connected to the server
via 4
dual port HBAs. The limiting factor in these tests is that any sin-
gle path to the SAN has a maximum capacity of around 200MB/Sec, which is the approximate
max throughput of a single 2 Gb fiber.
×
2Gbfibersonto2
×
Note that the random read and write times are very high. This is because when reading and writing large
blocks, you pay the price of just one costly seek, and then the remainder of the block is transferred by
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