So, a customer is experiencing slowness\/sluggishness in their app. You know there is not issue with the hypervisor from instinct, but instinct isn’t enough. Using tools like xentop, sar, bwm-ng are critical parts of live and historical troubleshooting. <\/p>\n
Sar can tell you a story, if you can ask the storyteller the write questions, or even better, pick up the book and read it properly. You’ll understand what the plot, scenario, situation and exactly how to proceed with troubleshooting by paying attention to these data and knowing which things to check under certain circumstances. <\/p>\n
This article doesn’t go in depth to that, but it gives you a good reference of a variety of tests, the most important being, cpu usage, io usage, network usage, and load averages. <\/p>\n
\r\n# Grab details live\r\nsar -u 1 3\r\n\r\n# Use historical binary sar file\r\n# sa10 means '10th day' of current month.\r\nsar -u -f \/var\/log\/sa\/sa10 \r\n<\/pre>\nCPU Usage of a particular Processor <\/h1>\n
\r\nsar -P ALL 1 1\r\n<\/pre>\n‘-P 1’ means check only the 2nd Core. (Core numbers start from 0).<\/p>\n
\r\nsar -P 1 1 5\r\n<\/pre>\nThe above command displays real time CPU usage for core number 1, every 1 second for 5 times.<\/p>\n
Observing Changes in Memory over time <\/h1>\n
\r\nsar -r 1 3\r\n<\/pre>\nThe above command provides memory stats every 1 second for a total of 3 times.<\/p>\n
Observing Swap usage over time <\/h1>\n
\r\nsar -S 1 5\r\n<\/pre>\nThe above command reports swap statistics every 1 seconds, a total 3 times.<\/p>\n
Overall I\/O activity <\/h1>\n
\r\nsar -b 1 3 \r\n<\/pre>\nThe above command checks every 1 seconds, 3 times.<\/p>\n
Individual Block Device I\/O Activities <\/h1>\n
This is a useful check for LUN , block devices and other specific mounts<\/p>\n
\r\nsar -d 1 1 \r\nsar -p d\r\n<\/pre>\nDEV – indicates block device, i.e. sda, sda1, sdb1 etc.<\/p>\n
Total Number processors created a second \/ Context switches <\/h1>\n
\r\nsar -w 1 3\r\n<\/pre>\nRun Queue and Load Average <\/h1>\n
\r\nsar -q 1 3 \r\n<\/pre>\nThis reports the run queue size and load average of last 1 minute, 5 minutes, and 15 minutes. \u201c1 3\u201d reports for every 1 seconds a total of 3 times.<\/p>\n
Report Network Statistics <\/h1>\n
\r\nsar -n KEYWORD\r\n<\/pre>\nKEYWORDS Available;<\/p>\n
DEV \u2013 Displays network devices vital statistics for eth0, eth1, etc.,
\n EDEV \u2013 Display network device failure statistics
\n NFS \u2013 Displays NFS client activities
\n NFSD \u2013 Displays NFS server activities
\n SOCK \u2013 Displays sockets in use for IPv4
\n IP \u2013 Displays IPv4 network traffic
\n EIP \u2013 Displays IPv4 network errors
\n ICMP \u2013 Displays ICMPv4 network traffic
\n EICMP \u2013 Displays ICMPv4 network errors
\n TCP \u2013 Displays TCPv4 network traffic
\n ETCP \u2013 Displays TCPv4 network errors
\n UDP \u2013 Displays UDPv4 network traffic
\n SOCK6, IP6, EIP6, ICMP6, UDP6 are for IPv6
\n ALL \u2013 This displays all of the above information. The output will be very long.<\/p>\n\r\nsar -n DEV 1 1\r\n<\/pre>\nSpecify Start Time <\/h1>\n
\r\nsar -q -f \/var\/log\/sa\/sa11 -s 11:00:00\r\n<\/pre>\n\r\nsar -q -f \/var\/log\/sa\/sa11 -s 11:00:00 | head -n 10\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"So, a customer is experiencing slowness\/sluggishness in their app. You know there is not issue with the hypervisor from instinct, but instinct isn’t enough. Using tools like xentop, sar, bwm-ng are critical parts of live and historical troubleshooting. Sar can … Continue reading