Hello,

I have EMC CX4-120. I have tested read/write performance of LUN:

LUN: raid10, 16x 400GB 15K HDD, read/write cache enabled

Test HOST: Win 2008 R2, installed EMC PowerPath, FC 4Gbit connect to CX4 (4 ports), in PowerPath 4 active paths

I have used "SQLio" for testing:

WRITE:

-------------

c:\_SQLIO>sqlio -kW -s60 -frandom -o8 -b64 -LS -Fparam.txt
sqlio v1.5.SG
using system counter for latency timings, 1953183 counts per second
parameter file used: param.txt
file E:\testfile.dat with 20 threads (0-19) using mask 0x0 (0)
20 threads writing for 60 secs to file E:\testfile.dat
using 64KB random IOs
enabling multiple I/Os per thread with 8 outstanding
using specified size: 10000 MB for file: E:\testfile.dat
initialization done
CUMULATIVE DATA:
throughput metrics:
IOs/sec:  2627.66
MBs/sec:   164.22
latency metrics:
Min_Latency(ms): 12
Avg_Latency(ms): 60
Max_Latency(ms): 591
histogram:
ms: 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24+
%:  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0 99
--------------

READ:

--------------

c:\_SQLIO>sqlio -kR -s60 -frandom -o8 -b64 -LS -Fparam.txt
sqlio v1.5.SG
using system counter for latency timings, 1953183 counts per second
parameter file used: param.txt
file E:\testfile.dat with 20 threads (0-19) using mask 0x0 (0)
20 threads reading for 60 secs from file E:\testfile.dat
using 64KB random IOs
enabling multiple I/Os per thread with 8 outstanding
using specified size: 10000 MB for file: E:\testfile.dat
initialization done
CUMULATIVE DATA:
throughput metrics:
IOs/sec:  5244.26
MBs/sec:   327.76
latency metrics:
Min_Latency(ms): 1
Avg_Latency(ms): 29
Max_Latency(ms): 312
histogram:
ms: 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24+
%:  0  0  0  0  0  0  0  0  1  1  0  0  1  1  1  2  3  3  4  4  4  5  5  5 61
-------------------

In PowerPath(Win 2008 host), I see 2 paths with IO/Sec (SP-A0,SP-A1) , owner of LUN is SP-A.

Why WRITE(164.22 MB/s) is only 1/2 of READ(327.76 MB/s) ?

What speed has internal interconnect between SP-A and SP-B ?

Thanks for answer.