02-20-2001 04:53 AM
3- 9Gb hard disk
1- 36Gb hard disk
Total: 63Gb hard disk and we have 384Mb of RAM Memory and 150 users aproximately.
How can we know the amount of RAM Memory that we need to be able to gestion the hard disk we have?. Thanks
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02-20-2001 05:48 AM
20 Mb for the resident OS
16 more Mb if any appreciable networking ... VT sessions,shareplex,sna etc.
1-2 Mb per session ... 1 Mb if 3GL (cobol, pascal), Vplus, TurboImage,NM etc..
2 Mb if 4GL (Cognos,Oracle),SQL, CM, etc..
2-4 MB per active Job ... Same criteria as for sessions.
All of this is with a minimum of 64 Mb.
Using this guideline you seem to be fine with the ram you have at this current time.
150 sessions x 2 = 300
20 for the os 20
16 for networking 16
10 active jobs x4 40
But to have more will not hurt.
02-20-2001 08:29 AM
The more memory you put in a machine the better the performance. The reason for this is that going out to disk for swapping and bringing in data to be processed is the slowest activity on the system.
If you have Glance/iX, SOS or any other performance tool you can tell how memory pressure is affecting performance. A *rough* guide for a K class box (989-650) using SOS would be
<4% you're ok
4%-8% moderate load
8%-12% heavy load
>12% excessive load
using Glance/ix use the xpert feature and go by it's messages.
FYI, our shop runs 3.75 gigabytes in each machines and we have 4 more gigabytes ready to install when we go to MPE 6.5. We practice what we preach.
02-20-2001 01:32 PM
AS others have said, more memory will assist in your systems performance. How much is dependent upon the type of application workload you are running and what software you use. In Lund's SOS product, there are, in my opinion 4 keys to verify if you have enough memory. 1. Memory Manager utilization, IMHO less than 2%; 2. Read Hit ratio, anything less than 95% could be aproblem; 3. page faults; and 4. memory clock cycles, lower the number is better. Having more memory will help reduce the I/O that the CPU needs to perform.