https://community.hpe.com/t5/operating-system-linux/free-v-sar/m-p/4757079#M43719 keep in mind that the first line of free command includes the allocated cache.<BR /><BR />linux will use all available mem for cache and give back as needed.<BR /><BR /><BR />look at the -/+ buffers/cache line for the real numbers.<BR /><BR /><BR /> Wed, 23 Feb 2011 17:24:26 GMT Tim Nelson 2011-02-23T17:24:26Z https://community.hpe.com/t5/operating-system-linux/free-v-sar/m-p/4757078#M43718 Hi,<BR /><BR />I had a server that experienced a crash last night and when I looked at the SAR report it showed that the "%memused" was 98%. On comparing this today with the memory info displayed from the "free" command, there appears to be a considerable difference (See below). Can anybody explain what the difference is between the two and what is the true reflection of what memory the box is using?<BR /><BR /># sar -r -f /var/log/sa/sa23 (shows "memused" @ 79%:<BR /><BR />03:35:01 PM kbmemfree kbmemused %memused kbbuffers kbcached kbswpfree kbswpused %swpused kbswpcad<BR />03:40:01 PM 9198600 56784520 86.06 630044 21133808 65535992 0 0.00 0<BR />03:45:01 PM 9195232 56787888 86.06 630292 21134048 65535992 0 0.00 0<BR />03:50:01 PM 9170532 56812588 86.10 630584 21133872 65535992 0 0.00 0<BR />03:55:01 PM 9149868 56833252 86.13 630856 21134152 65535992 0 0.00 0<BR />Average: 13659699 52323421 79.30 554684 19173568 65535992 0 0.00 0<BR /><BR />However free only suggests that the box is using 53%:<BR /><BR />[root@fworksdb2 ~]# free -b|grep ^-|awk '{ print (($3/($3+$4))*100) "% Used" }'<BR />53.1834% Used<BR /><BR />Rgds,<BR />D.<BR /> Wed, 23 Feb 2011 16:08:28 GMT https://community.hpe.com/t5/operating-system-linux/free-v-sar/m-p/4757078#M43718 Duffs 2011-02-23T16:08:28Z https://community.hpe.com/t5/operating-system-linux/free-v-sar/m-p/4757079#M43719 keep in mind that the first line of free command includes the allocated cache.<BR /><BR />linux will use all available mem for cache and give back as needed.<BR /><BR /><BR />look at the -/+ buffers/cache line for the real numbers.<BR /><BR /><BR /> Wed, 23 Feb 2011 17:24:26 GMT https://community.hpe.com/t5/operating-system-linux/free-v-sar/m-p/4757079#M43719 Tim Nelson 2011-02-23T17:24:26Z