DataDirect Networks S2A9550, User Manual

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M a n a g i n g t h e S 2 A 9 5 5 0
D a t a D i r e c t N e t w o r k s S 2 A 9 5 5 0 U s e r G u i d e
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3.3.4 System Performance Statistics
The S2A9550 monitors pre-fetch and cache efficiency, request distribution, transaction, and transfer
rates by port.
The
STATS
command will display the performance statistics for the host ports, disk channels, and
cache memory
(Figure 3-33)
. It will show the read and write performance of each of the host ports.
Read Hits shows the percentage of read I/O requests where the data was already in the cache.
Prefetch Hits shows the percentage of read I/O requests where the data was already in the cache
because of prefetching. Prefetches shows the percentage of host read I/O requests to the disks which
are due to prefetching.
The bottom of the screen shows the read and write performance of the disks. Disk Pieces shows the
total number of disk I/O requests from the host ports. The system will combine several host I/O
requests into a single disk I/O request. The histogram at the lower right shows how often this is
occurring for reads and writes. BDB Pieces is the number of host I/O blocking and deblocking
requests.
Cache Writeback Data shows the percentage of the cache which contains writeback data that must
be written to the disks. Cache Rebuild Data shows the percentage of the cache in use for rebuild
operations. Cache Data Lock shows the percentage of the cache which is locked by the locked LUNs.
The STATS CLEAR command will reset all the statistics back to zero.
The STATS DELAY command will display a histogram of the time it takes for the host and disk I/O
requests to complete in 100 msec intervals
(Figure 3-34)
.
System Performance Statistics
All Ports
Figure 3-33 System Performance Statistics Screen
S2A [1]: stats
Port 1 Port 2
Read MB/s:
Port 3 Port 4
4.6 1.0 3.7 0.0 0.0
Write MB/s: 36.9 24.1 12.8 0.0 0.0
Total MB/s: 41.5 25.0 16.5 0.0 0.0
Read IO/s: 932 17 915 0 0
Write IO/s: 657 386 271 0 0
Total IO/s: 1590 404 1186 0 0
Read Hits: 70.4% 92.0% 69.9% 0.0% 0.0%
Prefetch Hits: 46.8% 68.0% 46.4% 0.0% 0.0%
Prefetches: 5.7% 16.7% 5.4% 0.0% 0.0%
Writebacks: 100.0% 100.0% 100.0% 0.0% 0.0%
Rebuild MB/s: 0.0 0.0 0.0 0.0 0.0
Total Reads Writes
Disk IO/s:
Pieces Reads
576 334 242 1: 4995678
Writes
2636344
Disk MB/s: 83.2 42.8 40.4 2: 361919 253470
Disk Pieces: 13335378 6250849 7084529 3: 23056 14424
DBD Pieces: 299526 4: 27414 253470
5: 26043 10836
6: 18301 10176
Rebuild/Verify data: 0.0% 0.0% 7: 11152 10628
Cache Data locked: 0.0% 8: 4303 451177
Cache Writeback data: 74.4%
Verify MB/s: 0.0 0.0 0.0 0.0 0.0