SWAP space and RAM size

Hi all,
However there is no specific measurement for providing SWAP space,there is a ganeral rule says that "SWAP space must be twice the amount of RAM"...Why this specific value(twice of RAM)..Why it cant be the thrice amount? May i know what is the reason for telling this rule?
Please can anyone tell me?
Jasmine

Hi
The minimum requirement should be twice the size of RAM.This is because when a core dump occurs the whole active process avaulable in RAM will be written as a core file .the file will be initially written in the swap.The swap has to hold the full amount of memory and inturn swap will also have some files active.So as a minimum requirement you should have twice the amount of RAM as Swap Space.If you have a high storage and you dont know what to do give to to swap,No issue in that.

Similar Messages

Is useing swap space and hibernation secure?

As I understand it when you hibernate your system the ram is written to the swap space and the computer powers down. Is this secure and encrypted?

seniorsassycat wrote:As I understand it when you hibernate your system the ram is written to the swap space and the computer powers down. Is this secure and encrypted?
No, it is not. But are ypou running arch from an encrypted filesystem? Otherwise it would be pojntless. Anyway the normal swap is not encrypted either, at least by default.
Last edited by olive (2012-06-18 13:53:22)

CPU and RAM size for database

How can we see what is the CPU and RAM size for the database?
<div class="jive-quote">select * from v$version</div>
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bi
PL/SQL Release 10.2.0.5.0 - Production
CORE     10.2.0.5.0     Production
TNS for HPUX: Version 10.2.0.5.0 - Production
NLSRTL Version 10.2.0.5.0 - Production

cat /proc/meminfo
root:     total:      used:      free:           shared:     buffers:     cached:
Mem:      1055760384     1041887232     13873152     0     100417536      711233536
Swap:      1077501952      8540160      1068961792
MemTotal:          1031016 kB
MemFree:          13548 kB
MemShared:          0 kB
Buffers:          98064 kB
Cached:               692320 kB
SwapCached:          2244 kB
Active:               563112 kB
Inact_dirty:          309584 kB
Inact_clean:          79508 kB
Inact_target:          190440 kB
HighTotal:          130992 kB
HighFree:          1876 kB
LowTotal:          900024 kB
LowFree:          11672 kB
SwapTotal:          1052248 kB
SwapFree:          1043908 kB
Committed_AS:          332340 kB
cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 31
model name : AMD Athlon(tm) 64 Processor 3000+
stepping : 0
cpu MHz : 994.927
cache size : 512 KB
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce (snipped)
bogomips : 1956.97
TLB size : 1024 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp

Swap space and tempdb

Hi,
I'm having RAID 1 and RAID 5. RAID 1 is partitioned into 3 drive letters, C, D, and E. RAID 5 got only 1 partition, which is drive F. C for OS, D for SAP Kernel, E for Transaction Log and F for SAP Data.
In which drive should I allocate for swap space and tempdb? Of course for better performance I should have got separate hard disk for these, but unfortunately I can't.
Any suggestion.
BTW, my platform is Windows 2003 Enterprise and SQL Server 2005.
Rgds,
Hapizorr

Dear Hapizorr,
I recommend you review this document developed by Microsoft specifically for SAP systems:
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/4ab89e84-0d01-0010-cda2-82ddc3548c65
This will answer your question.
Thanks
N.P.C

How is SWAP space and Oracle's Shared Memory related ?

Platform: RHEL 5.4
Oracle Version: 11.2
I was trying to increase MEMORY_TARGET to 15g. Then I encountered the following error
SQL> alter system set memory_max_target=20g scope=spfile;
System altered.
SQL> alter system set memory_target=15g scope=spfile;
System altered.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL>
SQL>
SQL>
SQL> startup
ORA-32004: obsolete or deprecated parameter(s) specified for RDBMS instance
ORA-00845: MEMORY_TARGET not supported on this system
SQL>
SQL>
SQL> select name from v$database;
select name from v$database
ERROR at line 1:
ORA-01034: ORACLE not available
Process ID: 0
Session ID: 189 Serial number: 9From the below post
MEMORY_TARGET not supported on this system
I gathered that In Linux, if you want to set MEMORY_TARGET, MEMORY_MAX_TARGET to nGB , then you should have a SWAP ( /dev/shm ) of nGB.
My Swap was only 16gb and I was trying to set memory_max_target to 20g
$ df -h /dev/shm
Filesystem Size Used Avail Use% Mounted on
tmpfs 16G 7.2G 8.6G 46% /dev/shmNow, I am wondering how is Oracle's Shared Memory (SGA+PGA) related to SWAP space in a server ? Shouldn't Oracle's Shared Memory be related to Physical RAM rather than disk based SWAP space ?

related question:
In the above mentioned OTN article it says ,
You could encounter ORA-00845 if your shared memory is not mapped to /dev/shm
I think he meant
You could encounter ORA-00845 if your SWAP space is not mapped to /dev/shm .
Am I right ?

Table spaces and extent sizes

hi all,
how can we set the table spaces and extent sizes

Hi
All the things you can do when you are trying to create a table.
You create a table using SE11.
After that you have assign the fields to the table and later you need to give the technical settings to a table.
Here you need to specify the table size which you call it as Extents.
Table spaces are also defined to a table there itself.
Reward if useful

Premier Elements 12 - PC Windows 8.1 - plenty of disk space and RAM

I have been repeatedly getting the following error message when trying to burn a DVD. The error happens on a mix of different file sizes. Sometimes the system works correctly.
internal software error:\Vobulator\BlockPlanner\BlockPlanner.cpp,line 215
Can someone please point me in the direction of a fix?
Many thanks
Andrew

Hi
Thanks again and apologies for the delay in reply.
I use a Video Training DVD and therefore a link is not available.
I have found the tutorial helpful but did put a literal interpretation on the use of stop markers.
In Premier itself there is the selection : Stop Marker (for DVD only) – Returns to the Main Menu.
I assumed that the Stop Marker was needed to finish off the job and return to the Main Menu.
After what you told me that is not the case.
In one or two of my smaller sized videos the system did not object to the use of Stop Markers.
I was able to burn DVDs and that confused me.
On the Tutorial DVD the topic is covered in chapter 10 06 Creating a Movie Menu.
Kind regards
Andrew

Lumia 720 and RAM size

Dear All;
I was quite happy when I heared about Lumia 720 which was matching my requirement in terms of dimentions, weight and battery, but it was a shock for me to know the RAM is only 512??!!!!!!
I'm concerned about the performance and the future support for WP8. Will such small RAM be sufficient for the phone to perform without any lags??? ant what about the future support for WP8 as microsoft stated very clearly in their website that some apps and fetures will require 1 GB RAM, see link below (end of the page)
http://www.windowsphone.com/en-GB/how-to/wp8/start/whats-new-in-windows-phone
Regards

Well, it's good to see you are still here then.. That said, could you elaborate on what 'one of those' means and why you think that would suit you better? What we have now is 'Would having 512MB RAM be an issue' to which the answer basically is no, except you may not be able to use some of the more resource hungry apps like some games. It will not in any way prevent the phone from everyday use.
We would assume you refer to Android phones and in the same price range you'll get a decent mid range phone but not with a feature set the 720 offers. That said if you prefer that, that's perfectly fine and all the best with that, but so far it would seem you reason and decide based on specs alone which would IMO be not the best way to choose your weapon of choice.
Click on the blue Star Icon below if my advice has helped you or press the 'Accept As Solution' link if I solved your problem..

How do I keep Warp Stabilizer and aeselflink from filling my swap space?

Hello,
I'm running the lastest version of AE on OS X, when I try and run warp stabilizer on a composition, aeselflink grows the virtual memory it uses (> 50GB) until it fills my swap space and causes my machine to hang, because the hard drive is full.
Running AE's Edit->Purge options has no effect on the amount of virtual memory used. I have to quit AE to get aeselflink to quit and free the memory used. How can I limit the virtual memory used by aeselflink to something reasonable?

I'm not aware of a way to control this in any more detail, but this stuff obeys the settings you make in the Render Multiple Frames Simultanuously prefs if used. Otherwise it will use factory defaults which should never use more than 4GB. Anyway, the behavior you see is highly irregular no matter what. Sounds like a memory leak, so maybe you can provide more info, including which AE version, what footages etc.
Mylenium

Difference between page file and swap space

Hello friends
What is difference between swap space and page file???
I set the page file to 0 MB(No page file) but when I use Everest Software it show 1023 MB swap Space.Is there difference between them?

Swapping meaning data in and out from memory ie. primary to secondary. Paging is also the same thing, but its mostly used nowadays as virtual memory is based on pages. So, its like pages in and out. Swap space the memory used for swapping entire processes
from system memory into the swapfile. Where as paging transfers the pages to page file when the memory is almost full.
Regarding Everest, I think you should check with the supplier.
Arnav Sharma | Facebook |
Twitter Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members
reading the thread.

Problem with swap space

Hi All,
Using Oracle 10gR1, Solaris 9.
prtconf | grep "Memory size"
Memory size: 16384 Megabytesswap space is 16g
Pga_aggregate_target = 2G and after checking the v$pga_target_advice, it shows optimal.
Currently we have a issue of swap space getting used up nearly 100%. The system was out of memory and can't run any application
Alert logs error;
ORA-07445: exception encountered: core dump [_aio_free_stack_unlocked()+72] [SIGBUS] [Object specific hardware error] [0xFFFFFFFF7B602000] [] []
ORA-00600: internal error code, arguments: [ksnpost:ksnigb], [], [], [], [], [], [], []
ORA-04030: out of process memory when trying to allocate 588408 bytes (pga heap,kco buffer)On checking Metalink note, it said its an unhandled Oracle exception; have to increase the swap space.
AWR excerpt;
Cache Sizes (end)
~~~~~~~~~~~~~~~~~
               Buffer Cache:     4,848M      Std Block Size:         8K
           Shared Pool Size:     3,985M          Log Buffer:     1,024K
Load Profile
~~~~~~~~~~~~                            Per Second       Per Transaction
                  Redo size:             63,328.92              2,116.68
              Logical reads:              4,946.83                165.34
              Block changes:                257.73                  8.61
             Physical reads:              1,267.50                 42.36
            Physical writes:                 72.44                  2.42
                 User calls:                385.83                 12.90
                     Parses:                 84.22                  2.81
                Hard parses:                  0.04                  0.00
                      Sorts:                 10.53                  0.35
                     Logons:                  0.14                  0.00
                   Executes:                211.35                  7.06
               Transactions:                 29.92
% Blocks changed per Read:    5.21    Recursive Call %:    13.56
Rollback per transaction %:    0.29       Rows per Sort:    94.72
Top 5 Timed Events
~~~~~~~~~~~~~~~~~~                                        % Total
Event                                 Waits    Time (s)   DB Time     Wait Class
row cache lock                       16,498      45,001     43.44    Concurrency
log file switch (checkpoint in       30,766      30,281     29.23 Configuration
db file sequential read           2,873,716      10,796     10.42       User I/O
buffer busy waits                     8,870       8,718      8.42    Concurrency
db file parallel write                  421       3,848      3.71     System I/O
          -------------------------------------------------------------On increasing the swap space, and restarting the instance, the system was normal.
Now why does oracle use up all the swap space and what can be the workaround to avoid this in future?

Verma wrote:
Using Oracle 10gR1, Solaris 9.
swap space is 16gOracle 10gR2 swap space recommendations are:
- 1 GB - 2 GB = 1.5 times the size of RAM
- 2 GB - 8 GB = equal to the size of RAM
- Greater than 8GB = 0.75 times the size of RAM
Currently we have a issue of swap space getting used up nearly 100%. The system was out of memory and can't run any applicationThat is unusual and should not be happening when you have what seems to be an excess of memory available. This could mean some kind of bug (memory leakage for example), or it could mean plain old fashion abuse of memory. Like PL/SQL code that attempts to bulk fetch a few million rows from the database with a single go.
On checking Metalink note, it said its an unhandled Oracle exception; have to increase the swap space.Wrong IMO (unless you were not following the recommended swap size factor). If you have have a giant swap area..moving the wall a few meters away (by increasing swap) will only enable you to run faster into it - I doubt that this is the intent of that Metalink note.
On increasing the swap space, and restarting the instance, the system was normal.
Now why does oracle use up all the swap space and what can be the workaround to avoid this in future?Oracle only use what is needed to perform the client requests that it receives. If the client request a mountain of data to be moved/processed, Oracle will try to oblige. If that mountain topples and crushes server resources, it is not Oracle that is to blame for trying to do exactly what was requested from it.

Available swap space problem in solaris 10

Dear All,
Currently I am facing a most interesting problem regarding swap space.
We have assigned mirrored slice swap space with 20G size. But when we are asking for swap space it is only showing around 2GB.
1. Please have the swap area:
root@palash # swap -l
swapfile dev swaplo blocks free
/dev/md/dsk/d1 85,1 16 41945456 35002784
root@palash # swap -s
total: 53562072k bytes allocated + 5689008k reserved = 59251080k used, 615704k available
2. Please have the metastat output:
root@palash # metastat d1
d1: Mirror
Submirror 0: d11
State: Okay
Submirror 1: d21
State: Okay
Pass: 1
Read option: roundrobin (default)
Write option: parallel (default)
Size: 41945472 blocks (20 GB)
d11: Submirror of d1
State: Okay
Size: 41945472 blocks (20 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c0t0d0s1 0 No Okay Yes
d21: Submirror of d1
State: Okay
Size: 41945472 blocks (20 GB)
Stripe 0:
Device Start Block Dbase State Reloc Hot Spare
c0t1d0s1 0 No Okay Yes
3. Here is /etc/vfstab entry for swap:
/dev/md/dsk/d1 - - swap - no -
4. But when we checked swap space using df command:
root@palash # df -h
Filesystem size used avail capacity Mounted on
/dev/md/dsk/d0 18G 7.7G 9.9G 44% /
/devices 0K 0K 0K 0% /devices
ctfs 0K 0K 0K 0% /system/contract
proc 0K 0K 0K 0% /proc
mnttab 0K 0K 0K 0% /etc/mnttab
swap 1.7G 1.7M 1.7G 1% /etc/svc/volatile
objfs 0K 0K 0K 0% /system/object
sharefs 0K 0K 0K 0% /etc/dfs/sharetab
/platform/sun4u-us3/lib/libc_psr/libc_psr_hwcap1.so.1
18G 7.7G 9.9G 44% /platform/sun4u-us3/lib/libc_psr.so.1
/platform/sun4u-us3/lib/sparcv9/libc_psr/libc_psr_hwcap1.so.1
18G 7.7G 9.9G 44% /platform/sun4u-us3/lib/sparcv9/libc_psr.so.1
fd 0K 0K 0K 0% /dev/fd
swap 1.7G 184K 1.7G 1% /tmp
swap 1.7G 64K 1.7G 1% /var/run
/dev/dsk/c2t40d0s4 20G 20M 19G 1% /redo2
/dev/dsk/c2t40d0s1 276G 223G 50G 82% /oradata2
/dev/dsk/c3t40d0s3 195G 198M 193G 1% /restore
/dev/dsk/c2t40d0s0 276G 216G 57G 80% /oradata1
/dev/dsk/c2t40d0s5 59G 60M 58G 1% /system1
/dev/dsk/c3t40d0s0 276G 220G 53G 81% /index1
/dev/md/dsk/d3 30G 24G 5.7G 81% /oracle
/dev/dsk/c3t40d0s1 197G 53G 142G 28% /archive1
/dev/dsk/c2t40d0s3 20G 20M 19G 1% /redo1
/vol/dev/dsk/c0t6d0/disk1
0K 0K 0K 0% /cdrom/disk1
Please help me to indentify the reason.

918597 wrote:
Hello,
Thanks for your reply.
But I am not clear about your findings as we have around 64GB physical RAM in my machine.
My question is that if we mount 20GB swap partition, then how we can see this is around less than 2 GB in df -h command.
And even in swap -s command, this is showing same problem.
What might be reason behind this????
//PalashWell no-one else has anwered ... so its back to me.....
Hmmm ... i would use the word observations rather than findings .... I am not on an old root explotation expedition all over our server .. merely observing on the morsels you show me ....
Please be aware I may not be totally technically correct or be using right terminology on what follows so I welcome corrections ....
Your machine has 64GB Memory, and a 20 GB swap file, therefore has the ability up to support 84GB total (Virtual) Memory ofr it's processes/buffers.
The reason little swap is free (let us say 2GB ... thoug it may be 600m) is theat processes/buffers have a virutal memory requirement of 84GB-2GB = 82Gb.
... So rather than wondering about how come 2GB is left, start thinking about ow 82GB is being used.
...... Particularly with databases oracle RDBMS; mysql etc a big influencing factor can be how much memory is allocated its memory structures.
.......... And a DBA may set these extremely high (memory_max / innodb-buffer-pool-size etc etc).
ps -ef will show the (virtual) 'size' for individual processes
prstat -a may help show what is going on (but may double account some things):
ipcs -a would show the allocation for the oracle RDBMS memory_area,
echo ::memstat | mdb -k ### may help ... but i have seen accounts of it taking ages to run.
I'd also check kstat zfs ... but your not using zfs so no need to bother.
.... You may need to show some evidence of how your applications are consuming virutal memory for someone to help you futher ... but if you do htis who may answer your own quesiton.

Checking Swap space from OS level in HPUX

Hi All,
We have some issues with swap in our SAP production system when I checked the ST06 Tcode
Swap
Configured swap     Kb    20,971,520     Maximum swap-space Kb    54,389,460
Free in swap-space Kb     8,945,160     Actual swap-space   Kb    54,389,460
And when I checked from the OS level ,it gave me the following result
swapinfo
             Kb      Kb      Kb   PCT START/      Kb
TYPE      AVAIL    USED    FREE USED   LIMIT RESERVE PRI NAME
dev     1048576 658208 390368   63%       0       -    1 /dev/vg00/lvol2
dev     19922944 889824 19033120    4%       0       -    1 /dev/vg00/lvol9
reserve       - 19423488 -19423488
memory 33417940 24781076 8636864   74%
Does it mean that total swap space is (1048576 + 19922944)KB which is 20GB?
If yes ,then how to increase the swap space in UNIX based systems?
SWAP SPACE = 3*RAM? If yes ,do we need to put swap size =60 GB?
In ST06
what is the difference between CONFIGURED SWAP-SPACE and ACTUAL SWAP-SPACE?
Regards,
Prashant
Edited by: Prashant Shukla on Oct 13, 2008 4:21 AM
Edited by: Prashant Shukla on Oct 13, 2008 4:23 AM

Hi,
Thanks for ur reply but when I checked it from OS level why it is showing only 20GB ?
What's the diff between configured and actual swap space ?
I checked SAP Notes :146289 and 153641
They clearly says that swap space should be atleast 20 GB plus 10 GB for additional Instance for the server.
In our landscape we have CI and 4 dialog instance connected to it
that means our swap space should be 20 + 10*4=60 GB
We are having HPUX server and ST06 Swap values are
Swap
Configured swap     Kb    20,971,520   Maximum swap-space Kb    54,389,460
Free in swap-space Kb     8,697,960   Actual swap-space   Kb    54,389,460
Do we need to increase the SWAP Space to increase the system performance?
What is difference between configured swap and actual swap space ?
SAP Note 1112627 clearly says that SWAP SPACE = 2* RAM for HPUX servers.
What do you guys say about this?
Regards,
Prashant
Edited by: Prashant Shukla on Oct 13, 2008 5:15 AM
Edited by: Prashant Shukla on Oct 13, 2008 5:53 AM

Swap Partitioning and multiple disks

Ok so I have been setting up a workstation with Arch Linux that has a total of 16GB of RAM and, because it will run very memory intensive applications we actually require a large swap partition. Because this may eventually get upgraded to even more RAM we decided to go with a 50 GB swap partition.
I also have two drives in the machine, the primary 500GB HDD and a smaller 250 GB HDD that we wanted to use for a /backup partition as well as swap space and so I set up the disks as follows:
sda (500 GB):
/ (30 GB Primary Partition)
/home (435 GB Primary Partition)
/usr/local (2 GB Primary Partition)
sdb (250 GB)
50 GB Primary swap partition
/backup (~200 GB Primary Partition)
Now when I am in gparted or cfdisk that is how these partitions show up. If I do a df I see
sda1, sda2, sda3, and sdb2 but instead of seeing what woul;d be sdb1 as a large swap I see an 8 GB swap listed as being mounted on /dev/shm (which I think is normal).
After reading this:
http://lissot.net/partition/partition-04.html
I think the problem is that I don't have a swap partition set on my 500 GB drive. It seems like any bootable drive needs a swap partition on it. Although my system boots fine and I haven't had any problems running it yet I do need to get this swap partition straightened out otherwise the machine will have issues when it is fully operational and running heavy jobs.
IS this the problem? And if so would the best way to fix it be to use parted to shrink my /home partition by a few GB and make a small swap partition on that drive at the end of the drive space? Right now it is laid out as:
|---------------- / ----------------| |---- /usr/local ----| |------------------------------------------ /home ------------------------------------------|
Suggestions, ideas?
Thanks

The output from free -m is:
<code>
total used free shared buffers cached
Mem: 16018 15372 645 0 91 14600
-/+ buffers/cache: 679 15338
Swap: 47685 0 47685
</code>
For comparison here is the output from my laptop (also Arch Linux):
<code>
total used free shared buffers cached
Mem: 2025 614 1411 0 12 232
-/+ buffers/cache: 370 1655
Swap: 1019 0 1019
</code>
It has an ~ 1GB swap partition but it's df also shows something at /dev/shm:
<code>
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 12G 7.6G 3.4G 70% /
none 1013M 0 1013M 0% /dev/shm
/dev/sda3 78G 28G 47G 37% /data
</code>
In gparted on my laptop /dev/sda2 is the swap partition with size: 1019 MB
Going by free -m on the workstation it looks like it is seeing the ~50 GB swap partition and it is mounted in /etc/fstab so perhaps I have nothing to worry about? Is it actually necessary that your bootable disk has a swap partition on it? Both disks (sda and sdb) actually have at least one partition flagged as bootable but sda (which has / and /home on it) didn't have a swap partition on that disk.
Thanks for all the help.

Swap space is reducing

Hello Sun Gurus,
I monitor swap space daily. From last 3-4 days I am finding that free swap sapce is reducing day by day. However, our system is stable and we haven't installed any new software/application on this.
Please tell me what is going wrong on the system.
Regards
Gaurav

Your system is probably doing just what it is supposed to do. Take a look at this article, it may explain what you're seeing.
http://www.sun.com/sun-on-net/itworld/UIR951001perf.html
Below is an excerpt, explaining why swap doesn't seem to clean itself up after closing an application:
Launch your application again. Notice that it starts up more quickly than it did the first time, and with less disk activity. The application code and its data files are still in memory, even though they are not active. The memory they occupy is not "free." If you restart the same application it finds the pages that are already in memory. The pages are attached to the inode cache entries for the files. If you start a different application, and there is insufficient free memory, the kernel will scan for pages that have not been touched for a long time, and "free" them. Once you quit the first application, the memory it occupies is not being touched, so it will be freed quickly for use by other applications.
In 1988, Sun introduced this feature in SunOS 4.0. It still applies to all versions of Solaris 1 and 2. The kernel is trying to avoid disk reads by caching as many files as possible in memory. Attaching to a page in memory is around 1,000 times faster than reading it in from disk. The kernel figures that you paid good money for all of that RAM, so it will try to make good use of it by retaining files you might need.
By contrast, Memory leaks appear as a shortage of swap space after the misbehaving program runs for a while. You will probably find a process that has a larger than expected size. You should restart the program to free up the swap space, and check it with a debugger that offers a leak-finding feature (SunSoft's DevPro debugger, for example).

SWAP space and RAM size

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