Red Hat

Dear All,

One of my Linux Server which is a Production server. I see always RAM is used fully. Eventhough Swap space is available , the system is extremely slow.

I have even cleared the cache memory , but still not RAM is reduced.

Kindly let me know if there are any solutions to bring down the RAM used.

Code:

[root@sun1 ~]# free -g
             total       used       free     shared    buffers     cached
Mem:            11         11          0          0          0          0
-/+ buffers/cache:         11          0
Swap:           18          2         16

Thanks and Regards
Rj

Please post some basic information:

1) What Operating System and version are running?

2) What is the specification of the hardware:
Make, model, RAM fitted, number of CPUs?

3) How much disc space is allocated to swap?
... and how much is used?

4) Have you changed any kernel parameters? If so, what were the old and new values and the reasoning behind the change?

5) What database software and version are you running?
Have you changed any database startup parameters? If so, what were the old and new values?
(A common problem is misunderstanding the units of database parameters and accidentally allocating more memory than you have fitted).

6) How many clients? ... and how do they connect to this server?

1. RHEL release 5.5 (Tikanga)

2.Linux sun1 2.6.18-194.el5 #1 SMP Mon Mar 29 22:10:29 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux

3. 8 Processors and each with 4 core processors,

4. 18 G is allocated to swap and 4 gig is used , 14 gig available.

5. No Kernel parameters changed.

6. Oracle 11 g is installed and other Datawarehousing softwares OBIEE 11g is installed in it.

7. There are no System clients for this Server.. Only Application Server clients are there which are to a maximum 50.

Pl guide me ..

Thanks and Regards
Rj

The Linux kernel is optimized to use as much RAM as possible. This is normal system behavior.

4 GB is not much RAM in a modern day system. Our web server uses 32GB. RAM is cheap. Buy more. Swapping to disk is slow. Don't design a server to use swap unless you want performance to slow down.

Get more than 4 GB of RAM, problem solved.....

Code:

Mem:  33011004k total, 28995776k used,  4015228k free,   348328k buffers
Swap: 19530748k total,    14212k used, 19516536k free, 24653588k cached

ya but it doesn't show any cache/buffer there... his system has 11G shown in free. if it is not expected to be using all of this RAM i'd have a look at top to make sure things are as expected. you cannot blame swapping for the slowness yet though. run vmstat 10 and it'll update every 10 seconds showing swaps in/out. paste a few lines of this.

but how did you 'clear the cache' ? having nothing cached will then mean more disk reads for file accesses, which is also going to slow you down. this will give you less RAM swapped out though, but you're really just moving the problem.

overall the easiest solution is adding RAM, unless you find you've improperly configured services, or non-essential ones, wasting your memory.

I agree with this. RAM is cheap; cheaper than hours of analysis. Heck, I have 4GB of RAM on my MBA which I only use for web and email; basically. Our basic server is now at 32 GB RAM...... so a running a server with an Oracle DB with only 4 GB of RAM seems "overly economical" to me..... It is cheaper to just put in more RAM than trying to analyze the issue to death... IMHO..

Dear All,

thanks for the information provided by you.

Thanks and Regards
JeganR