Windows 2003 Enterprise 32bit VM RAM can't go beyond 4GB & increasing vCPU slows VM
Posted on 2013-06-21
We have P2V'ed a Win2003 SP2 that run SQL 2005 to VM &
then run some batch jobs (SQL & Stored Procedures) that we
previously ran in the physical servers with same parameters
as what they used to run while on physical server for
comparison purpose to see if performance improves.
The SAN LUN which hold the DB is presented over to the
VM so that the P2V'ed VM can access it as RDM. Results of
the test showed it takes about the same amt of time.
Thereafter we shut down the VM, did 'Edit Settings" &
a) double the number of cores (to double the vCPU )
b) double the RAM to 8GB
After bootup, we noted under Computer Properties, the
# vCPU did double but the RAM stays at 4GB.
We did enable PAE on the Win 2003 but why is it the amt
of RAM did not reflect as 8GB? I can send you a screen
shot of the PAE setting if needed.
The link below indicates that with /PAE, it's suppose to be
able to go up to 64GB.
We then reran exactly the same stored procedure & SQL
jobs (with exact same parameters) but this time, it took
5-30% longer with one of the job giving the same amt
of timing. What could be the reason. The peak CPU for
this VM was 17% only while the jobs are being run as we
used Performance Chart to monitor while it's being run.
I read that increasing vCPU could be bad for performance
in some cases (in one past EE thread that I saw) : under
what circumstances will it be slower?