Monitoring RAM resources of your VPS is very important. Especially, if you use caching systems such as Redis or Memcached. If your server runs out of memory, or runs short on memory, your website or service can stop or may run slow.<\/p>\n

Luckily, Linux gives you a few handy tools that you would need to monitor memory usage. These tools can be easily used from the command line. This short (and sweet) article will give you an idea how to use those commands, and you can pick the one that fits your needs the most.<\/p>\n

1. vmstat command<\/h3>\n

Type in\u00a0vmstat<\/code>\u00a0to your command line and the program will display how much free memory is available.<\/p>\n

root@localhost:\/# vmstat\r\nprocs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----\r\n r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st\r\n 3  0      0 185332  43880 150176    0    0     2     6    8    7  0  0 100  0  0\r\n<\/code><\/pre>\n
If you need more details, run vmstat with the\u00a0-s<\/code>\u00a0or\u00a0--stats<\/code>\u00a0parameter. Check the first line of the output to see how much free memory is available on your server.<\/p>\n
root@209:\/# vmstat -s\r\n759872  K total memory\r\n575220  K used memory\r\n356148  K active memory\r\n86168   K inactive memory\r\n184652  K free memory\r\n44048   K buffer memory\r\n149248  K swap cache\r\n0       K total swap\r\n0       K used swap\r\n0       K free swap\r\n806545  non-nice user cpu ticks\r\n1       nice user cpu ticks\r\n533833  system cpu ticks\r\n424692262 idle cpu ticks\r\n54982   IO-wait cpu ticks\r\n244344  IRQ cpu ticks\r\n0       softirq cpu ticks\r\n0       stolen cpu ticks\r\n7190421 pages paged in\r\n27240788 pages paged out\r\n0       pages swapped in\r\n0       pages swapped out\r\n335817481 interrupts\r\n285597986 CPU context switches\r\n1425579890 boot time\r\n332134  forks\r\n<\/code><\/pre>\n
2. top command<\/h3>\n
This is a widely known command to check both memory and CPU usage.<\/p>\n
top - 03:20:50 up 49 days,  8:55,  1 user,  load average: 0.00, 0.01, 0.05\r\nTasks:  87 total,   1 running,  86 sleeping,   0 stopped,   0 zombie\r\n%Cpu(s):  0.3 us,  0.3 sy,  0.0 ni, 99.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st\r\nKiB Mem:    759872 total,   576156 used,   183716 free,    44628 buffers\r\nKiB Swap:        0 total,        0 used,        0 free.   149652 cached Mem\r\n\r\nPID USER      PR  NI    VIRT    RES    SHR S %CPU %MEM     TIME+ COMMAND\r\n1 root      20   0   36284   5312   1192 S  0.0  0.7   0:42.98 init\r\n2 root      20   0       0      0      0 S  0.0  0.0   0:00.00 kthreadd\r\n3 root      20   0       0      0      0 S  0.0  0.0   0:05.13 ksoftirqd\/0\r\n5 root       0 -20       0      0      0 S  0.0  0.0   0:00.00 kworker\/0:0H\r\n<\/code><\/pre>\n
3. free command<\/h3>\n
This is my favorite, and probably the most simple command to view memory stats.<\/p>\n
root@209:\/# free -m\r\n              total       used       free     shared    buffers     cached\r\nMem:           742        562        179         27         43        146\r\n-\/+ buffers\/cache:        372        369\r\nSwap:            0          0          0\r\n<\/code><\/pre>\n
The example above shows you how much total memory your VPS has (in Megabytes), how much memory is used, and how much memory is free.<\/p>\n
4. htop command<\/h3>\n
This command is similar to the\u00a0top<\/code>\u00a0command, but in my opinion, it gives you a better idea about the memory state of your server.<\/p>\n
Conclusion<\/h3>\n
The commands listed above can be used to manually monitor memory usage. You can also write a simple script using your preferred programming language to run these commands and alert you (by email, for example) if your memory resources are low.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"open","ping_status":"closed","template":"","format":"standard","manualknowledgebasecat":[242],"manual_kb_tag":[485],"_links":{"self":[{"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/manual_kb\/2983"}],"collection":[{"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/manual_kb"}],"about":[{"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/types\/manual_kb"}],"author":[{"embeddable":true,"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/comments?post=2983"}],"version-history":[{"count":1,"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/manual_kb\/2983\/revisions"}],"predecessor-version":[{"id":2984,"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/manual_kb\/2983\/revisions\/2984"}],"wp:attachment":[{"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/media?parent=2983"}],"wp:term":[{"taxonomy":"manualknowledgebasecat","embeddable":true,"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/manualknowledgebasecat?post=2983"},{"taxonomy":"manual_kb_tag","embeddable":true,"href":"https:\/\/support.aklwebhost.com\/wp-json\/wp\/v2\/manual_kb_tag?post=2983"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}