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How to determine really the actual amount of RAM used?

Posted on 2008-10-10
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How to determine really the actual amount of RAM used in Solaris 9.

is vmstat really reports both RAM + SWAP?

what does the "free" column really mean? is it both RAM + SWAP?

kthr      memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr m0 m1 m3 m6   in   sy   cs us sy id
 0 0 0 4539008 484280 4  19  2  1  1  0  0  0  0  0  0 1171  658  731  5  1 94

TIA
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Question by:migraine007ph
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by:omarfarid
ID: 22693991
Can you try using top (you may download from sunfreeware.com)?
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by:blu
ID: 22696063
It somewhat difficult to determine how much RAM is in use in older versions of Solaris. The algorithms used by the memory system were changed at virtually each release and the tools were also moving targets. The thing is that Solaris always uses all of the RAM that is available for file system buffers. Any time there is I/O, the data is left in a RAM page in case it might be needed later. If a page is needed for program memory, then the page is flushed. So, once there is I/O going on, the RAM is always allocated.

The best way to determine if there is a shortage of memory is to look at the SR entry from vmstat. This stat indicates the number of times in the period that the a page was needed but was not immediately available, causing the page scanner to scan through the pages looking for the least recently used pages to force out and replace. As long as SR is zero or very small, you have not run out of memory.
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by:migraine007ph
ID: 22696290
really????

@blu, re "somewhat difficult to determine how much RAM is in use in older versions of Solaris."

1. does this include solaris 9?
2. how did you know btw this?
3. so, solaris has issues then on reporting memory usages, is there any patches / kernel upgrades for this one?
4. what does the "free" column really mean? is it both RAM + SWAP?


many thanks man/.

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Author Comment

by:migraine007ph
ID: 22696393
i have these vmstat output... can some one interpre to me what these mean?

bash-2.05# vmstat 5
 kthr      memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr m0 m1 m3 m4   in   sy   cs us sy id
 0 0 0 4163592 382632 14 48 40 45 46  0  2  0  0  0  0  571 1013 1246  2  2 96
 0 0 0 3554744 30320 140 40 415 1266 1266 0 0 0 0 0  0  953 12395 5432 15 8 76
 0 0 0 3552896 29888 85  10  3 1057 1057 0 0 0 0  0  0  832 7878 3869 11  7 82
 0 0 0 3553216 30552  3   0  0 56 56  0  0  0  0  0  0  529  940 1044  1  1 99
 0 0 0 3553208 30608  4   1 18 45 45  0  0  0  0  0  0  501  871  981  1  1 98
 0 0 0 3553208 30616  3   8  2 30 30  0  0  0  0  0  0  546 1346 1267  2  2 96
 0 0 0 3557064 34768  3   6 19  0  0  0  0  0  0  0  0  524  878  996  1  1 99
 0 0 0 3554456 32928 21 300 171 0  0 19072 0 0 0  0  0  489 1028  966  1  1 97
 0 0 0 3553568 32192 30 134 11  2  2 11280 0 0 0  0  0  579 1946 1342  2  3 95
 0 0 0 3553568 32144  0   0  3  2  2 6680 0 0  0  0  0  527  854  968  0  1 99
 0 0 0 3553032 31584 98  39 221 722 722 3960 0 0 0 0 0 1030 15669 6901 21 9 70
 0 0 0 3554072 31816 17   1 414 0  0 2352 0 0  0  0  0  968 10561 4794 14 8 78
 0 0 0 3555152 32008 47 111 208 8  8 1400 0 0  0  0  0 1008 14157 5956 17 9 74
 0 0 0 3554536 30472 163 43 410 1199 1199 600 0 0 0 0 0 1331 21839 8995 27 15 57
 0 0 0 3553176 30376 172  7  6 1539 1560 0 23 0 0 0  0 1307 19399 8335 27 15 58
 0 0 0 3555608 31824 11   1 410 0  0  0  0  0  0  0  0  786 6304 3199  8  4 88
 0 0 0 3555608 31664  4   0  5  0  0  0  0  0  0  0  0  525  799  933  0  1 99
 0 0 0 3555608 31544  0   3  3  0  0  0  0  0  0  0  0  508 1202 1199  2  1 97
 0 0 0 3555608 31496  0   1  5  0  0  0  0  0  0  0  0  527  815  938  0  1 99
 kthr      memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr m0 m1 m3 m4   in   sy   cs us sy id
 0 0 0 3559176 34336  4   7 13  2  2  0  0  0  0  0  0  501  781  896  0  1 99
 0 0 0 3556496 32144 61 477 56  6  6 19072 0 0 0  0  0  562 2368 1535  4  3 93
 0 0 0 3555608 31352  1   1  5  0  0 11280 0 0 0  0  0  551 1036 1062  1  1 99
 0 0 0 3554776 30576 147 42 206 1234 1234 6680 0 0 0 0 0 1108 15824 6663 21 10 69
 0 0 0 3552408 29248 112 16 11 1162 1231 3960 76 0 0 0 0 906 9440 4327 11 7 82
 0 0 0 3554440 30992 46 213 18 16 16 2352 0 0  0  0  0  616 3008 1810  6  2 92
 0 0 0 3555064 30816 111 45 310 1196 1496 1400 305 0 0 0 0 1014 13426 5825 17 10 73
 0 0 0 3553096 31120 12   7 50 91 91 600 0  0  0  0  0  863 7025 3499  8  7 85
 0 0 0 3553608 31280  0   0  0  3  3  0  0  0  0  0  0  564  863 1073  0  1 99
 0 0 0 3553608 31080  3   0  2  0  0  0  0  0  0  0  0  518  818  956  0  1 99
 0 0 0 3553608 30968  0   3  3  0  0  0  0  0  0  0  0  586 1595 1406  2  1 97
 0 0 0 3553608 30896  0   0  0  0  0  0  0  0  0  0  0  513 1016 1110  1  1 97
 0 0 0 3553608 30864  1   0  3  0  0  0  0  0  0  0  0  578  812  951  1  1 98
 0 0 0 3553608 30776 29 135 11  0  0  0  0  0  0  0  0  593 1868 1280  2  3 95
 0 0 0 3553608 30720  0   0  2  3  3  0  0  0  0  0  0  515  803  916  1  1 98
 1 0 0 3553424 30552 120 24 212 998 998 0 0 0  0  0  0 1045 15866 6802 21 9 70
 0 0 0 3553096 30680 76  14  3 664 664 0 0  0  0  0  0  950 10185 4808 14 6 80
 0 0 0 3553488 30520 114 111 551 584 584 0 0 0 0  0  0 1255 20391 8300 24 13 63
 0 0 0 3552872 30280 198 45  6 1686 1686 0 0 0 0  0  0 1112 16856 7161 21 11 67
 kthr      memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr m0 m1 m3 m4   in   sy   cs us sy id
 0 0 0 3551360 29888 236  1 418 2210 2205 0 0 0 0 0  0 1310 18642 7932 23 15 62

from the looks of it seems to me is just normal, i have process under normal users only one is a  java and one from oracle, no heavy processes run on sys/root.

also look on hte free column,, seems odd, first row against the 2nd onwards....


many thanks.
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Author Comment

by:migraine007ph
ID: 22696395
btw, that machine has 4gb of swap and 2gb of ram. TIA
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Accepted Solution

by:
blu earned 500 total points
ID: 22712663
To answer your questions:

>1. does this include solaris 9?
Yes
>2. how did you know btw this?
Years of experience with Solaris.
>3. so, solaris has issues then on reporting memory usages, is there any patches / kernel upgrades for this one?
Nope.
>4. what does the "free" column really mean? is it both RAM + SWAP?
The combined size of the cache list and the free list.

The vmstat output does indeed look normal.

It is generally wise not to pay too much attention to the first line in any of the Solaris *stat commands, sometimes they
represent time since boot, sometimes they are from a shortened time period. Best to ignore them and start looking after
the 2nd line.
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