Where is my memory? How to fix it ?


 
Thread Tools Search this Thread
Operating Systems Solaris Where is my memory? How to fix it ?
# 1  
Old 08-13-2019
Where is my memory? How to fix it ?

Hello,

I have few Solaris 11.2 servers. Since sometime, we are noticing high memory utilization in them.
Here is current config

Code:
root@ser22-zonemgr:~# /tmp/memory.sh
        Physical memory size:            36864
        Memory usage in MB:              32938
        Memory usage in %:               89%
root@ser22-zonemgr:~#
root@ser22-zonemgr:~# echo ::memstat -v | mdb -k
Page Summary                 Pages             Bytes  %Tot
----------------- ----------------  ----------------  ----
Kernel                      721833              5.5G   15%
Guest                            0                 0    0%
ZFS Metadata                 74346            580.8M    2%
ZFS File Data               853646              6.5G   18%
Anon                       2351933             17.9G   50%
Exec and libs                 2369             18.5M    0%
Page cache                  222555              1.6G    5%
Free (cachelist)              4922             38.4M    0%
Free (freelist)             486988              3.7G   10%
Total                      4718592               36G
root@ser22-zonemgr:~#

From prstat -->
 NPROC USERNAME  SWAP   RSS MEMORY      TIME  CPU
   115 timesten   16G   15G    43%  76:49:22 1.6%
   106 root     2887M 2698M   7.3% 383:50:51 2.2%
     8 daemon     41M   56M   0.2%   1:15:31 0.0%
     8 pkg5srv    37M   38M   0.1%   1:07:26 0.0%
     8 john    12M   34M   0.1%   0:00:00 0.0%
     2 smmsp    3936K   13M   0.0%   0:03:25 0.0%
     2 netadm   3808K 9032K   0.0%   0:07:34 0.0%
     2 netcfg   2560K 6664K   0.0%   0:07:39 0.0%
     2 hspokes   2408K   15M   0.0%   0:00:00 0.0%
     2 noaccess 2088K 8096K   0.0%   0:00:02 0.0%

And here is from another server
Code:
ser42-zonemgr:~# /tmp/memory.sh
        Physical memory size:            16384
        Memory usage in MB:              14653
        Memory usage in %:               89%
ser42-zonemgr:~# echo ::memstat -v | mdb -k
Page Summary                 Pages             Bytes  %Tot
----------------- ----------------  ----------------  ----
Kernel                      674735              5.1G   32%
Defdump prealloc            119423            932.9M    6%
ZFS Metadata                111996            874.9M    5%
ZFS File Data               168163              1.2G    8%
Anon                        877423              6.6G   42%
Exec and libs                 2496             19.5M    0%
Page cache                   17788            138.9M    1%
Free (cachelist)                 7               56k    0%
Free (freelist)             216864              1.6G   10%
Total                      2097152               16G
ser42-zonemgr:~#

As I read few forums, I understood that the memory is filled with unmapped pages of data read from disk. It's kept in memory because those files may be read again and keeping the data in memory saves a disk read. That is where, OS is holding up memory. This is leaving less memory, which can be called as 'free'. Though whenever any application or DB needs that memory, OS will release. But our problem is, monitoring system. When total utilization hits 90% (right now it is 89%), it will page out SA.

What can be solution for this issue ?
Any recommendations ?

Thanks
# 2  
Old 08-13-2019
Hi,

There is an excellent Oracle Document covering this on the Oracle site Document ID 1663862.1 it give in depth information covering your monitoring issue.

This should at least point you in the right direction.

Due to the way that the MMU and ZFS behave, this can be an issue for monitoring tools.

I've also just noticed that you say that you've recently noticed the increase in memory utlisation, an other possible cause could be memory leakage caused by applications code not fully releasing memory. Do you have any trending information, does your monitoring tool produce such information - this is generally easy to see over a longer term.

Regards

Gull04

Last edited by gull04; 08-13-2019 at 04:18 AM.. Reason: More information.
These 2 Users Gave Thanks to gull04 For This Post:
# 3  
Old 08-13-2019
Thanks for document. This is really good one and gave valid information, also about benefits of 'user_reserve_hint_pct' over 'zfs_arc_max'.

However, I was getting some confused, what should I set initially as per my server's load and memory utilization. Because there are no previous/desired zfs_arc_max, so I can't user formula mentioned in this document. Should I start with 60 ? These are production servers, so a little of performance issue will raise some noises.

Tomorrow morning, I will request report from monitoring team, if they can give and that should help me to understand the trend.
# 4  
Old 08-13-2019
Hi,

I'm not really a great fan of trying things out on production servers, it always seems to come back and bite you from an other direction. If your environment is anything like most of the ones I have worked in over the years, test and development machines seem to be scarce and if they exist - getting testing resource is like finding a winning lottery ticket.

It's a difficult call for me, I don't know anything about your environment other than you are using Solaris 11.2, one server has 36Gb of memory, the other has 16Gb of memory and they could be whole root zones. And of course the fact that both servers are reporting almost 90% memory utilisation which will trigger an alert.

Much of this is going to come down to a few things here;
  1. Can you do this on a Test/Dev sever?
  2. Does going ove 90% memory utilisation cause a problem with the application.
  3. Can you live with the alert generated at the 90% threshold, can it be ignored or the threshold changed.
  4. Do you have to try this change in a production environment, if there are problems whats the regression?
  5. How critical is the production server, if it's critical could you test on the DR server?
  6. Will your boss back you up if you take the iteritive approach and set "user_reserve_hint_pct" to 60% as Oracle suggest.

I know the above isn't overly helpful, but asking someone with no experience of the environment in which you work just opens up many more questions than can't be easilly answered in a forum such as this.

My preferred approach to this would be to run an explorer over the system and raise a support ticket (case) with Oracle support, in the ticket you should cite your concerns - please be aware that Oracle may well come back and suggest things like the patching is brought up to date for the systems.

Regards

Gull04

Last edited by gull04; 08-13-2019 at 09:37 AM.. Reason: Can't Spell
This User Gave Thanks to gull04 For This Post:
# 5  
Old 08-13-2019
Thanks. I will follow it
Login or Register to Ask a Question

Previous Thread | Next Thread

9 More Discussions You Might Find Interesting

1. Solaris

[DOUBT] Memory high in idle process on Solaris 10 (Memory Utilization > 90%)

Hi Experts, Our servers running Solaris 10 with SAP Application. The memory utilization always >90%, but the process on SAP is too less even nothing. Why memory utilization on solaris always looks high? I have statement about memory on solaris, is this true: Memory in solaris is used for... (4 Replies)
Discussion started by: edydsuranta
4 Replies

2. Solaris

relationship or difference between entitled memory and locked memory

Hello solaris experts, Being new to solaris containers, from Linux, feeling difficulty in understanding certain concepts. Hope somebody can help me here. I understand that, & some questions .... Locked memory -- memory which will not be swapped out at any cause. is this for... (0 Replies)
Discussion started by: thegeek
0 Replies

3. UNIX for Advanced & Expert Users

Out of Memory error when free memory size is large

I was running a program and it stopped and showed "Out of Memory!". at that time, the RAM used by this process is around 4G and the free memory size of the machine is around 30G. Does anybody know what maybe the reason? this program is written with Perl. the OS of the machine is Solaris U8. And I... (1 Reply)
Discussion started by: lilili07
1 Replies

4. Solaris

restrcit physical memory with zone.max-locked-memory

Is it possible to restrict physical memory in solaris zone with zone.max-locked-memory just like we can do with rcapd ? I do not want to used rcapd (1 Reply)
Discussion started by: fugitive
1 Replies

5. Programming

How to deal with lots of data in memory in order not to run out of memory

Hi, I'm trying to learn how to manage memory when I have to deal with lots of data. Basically I'm indexing a huge file (5GB, but it can be bigger), by creating tables that holds offset <-> startOfSomeData information. Currently I'm mapping the whole file at once (yep!) but of course the... (1 Reply)
Discussion started by: emitrax
1 Replies

6. Solaris

How to find Total and Free Physical Memory and Logical Memory in SOLARIS 9

Hi, Im working on Solaris 9 on SPARC-32 bit running on an Ultra-80, and I have to find out the following:- 1. Total Physical Memory in the system(total RAM). 2. Available Physical Memory(i.e. RAM Usage) 3. Total (Logical) Memory in the system 4. Available (Logical) Memory. I know... (4 Replies)
Discussion started by: 0ktalmagik
4 Replies

7. AIX

ulimits max locked memory virtual memory

Hi, Would any one be so kind to explain me : are ulimits defined for each user seperately ? When ? Specialy what is the impact of : max locked memory and virtual memory on performance of applications for a user. Many thanks. PS : this is what I can see in MAN : ulimit ] ... (5 Replies)
Discussion started by: big123456
5 Replies

8. HP-UX

How can I get memory usage or anything that show memory used from sar file?

Refer from title: How can i get memory used or anything that can show memory from sar file example on solaris:- we can use sar with option to show memory used at time that sar crontab run. on HP-UX, it not has option to see memory used. But i think it may be have some parameter or some... (1 Reply)
Discussion started by: panithat
1 Replies

9. Programming

how to round up a memory address(memory alignment problem)

Hi, I try to marshal a unsigned int and a char * into a buffer, and then unmarshal them later to get them out. I need to put the char * in the front and unsigned int at the end of the buffer. However, my system always give me "BUS ERROR". I am using Sun Sparcs Sloris 2.10. My code to marshal... (6 Replies)
Discussion started by: nj302
6 Replies
Login or Register to Ask a Question