Hello,
The SAS3442X is connected to the JBOD via a x4 SAS cable.
The JBOD has an LSI SAS Expander chip - no port multiplier.
Disks are Seagate ST3300831AS (300 GB, SATA-I, NCQ)
Does the SAS controller and the SAS expander communicate at 3 Gb when
accessing SATA disks?
If not it should give 4 * 150 MB/s r/w throughput for this configuration.
I am testing with parallel dd invocations on the raw device e.g.:
dd if=/dev/sdb of=/dev/null bs=32k count=10000 &
...
dd if=/dev/sdl of=/dev/null bs=32k count=10000 &
I have tested with IOMETER but the results are worse.
I will test SATA II disks later. But I assume there is a scheduling
problem (mapping 10 disks to 4 channels). The CPU load is also very high.
Disks support NCQ but it should have no effect due to sequential access
of a single application per disk. How to switch on/off NCQ?
Regards,
Mirko
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