Suresh Thalamati wrote:
Olav Sandstaa wrote:
I have run some simple tests where I have changed mode from "rws" to
"rwd" for the Derby log file. When running a small numbers of
concurrent client threads the throughput is almost doubled and the
response time is almost halved. I am enclosing two graphs that show
this when running a given number of concurrent "tpc-b" clients. The
graphs show the throughput when running with "rws" and "rwd" mode
when the
disk's write cache has been enabled and disabled.
I am really surprised to notice the difference between rws / rwd
throughput in your graphs, Especially when the write cache is
enabled. When I ran small tests long time ago, did not notice any
substantial difference between rws/rwd, on windows for sure.
I was not surprised of the results with the disk's write cache disabled,
but very surprised by the large effect then the write cache was enabled.
I had expected to so hardly any difference in that case. This was on
Solaris 10, on Linux 2.6 I did not see any difference between these case
(both with and without a write cache on the disk).
Could u please post more details on the hardware/OS/JVM ..etc. and
The hardware is a dual Opteron server with two reasonable fast Fujitsu
SCSI disks (one for log and one for the database). If I remember
correctly the disks have a 6 MB cache (shared between reading and
writing), Solaris 10 x86 and Sun JVM 1.5 update 4.
What is the work done in each transaction ?
The transactions are similar to TPC-B trasactions. Each consists of
three updates, one insert and one select.
Olav
