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By default daily report are written to the file /var/log/sa/sar${DAY} by cron script that invokes sa2 (the second line invokes /usr/lib64/sa/sa2 )
Important part of implementation consist of scripts sa1 and sa2 that are invoked from cron, for example
# Activity reports every 10 minutes everyday */10 * * * * root [ -x /usr/lib64/sa/sa1 ] && exec /usr/lib64/sa/sa1 -S ALL 1 1 # Update reports every 6 hours 55 5,11,17,23 * * * root [ -x /usr/lib64/sa/sa2 ] && exec /usr/lib64/sa/sa2 -A
The reports are in binary format and can be read only by sar utility.
For example here how you can statistics for cpu:
[0]root@node16: # sar -u Linux 2.6.18-398.el5 (node16) 02/11/2015 12:00:01 AM CPU %user %nice %system %iowait %steal %idle 12:10:01 AM all 96.83 0.00 0.05 0.00 0.00 3.12 12:20:01 AM all 96.83 0.03 0.05 0.00 0.00 3.09 12:30:01 AM all 96.86 0.00 0.01 0.00 0.00 3.12 12:40:01 AM all 96.87 0.00 0.01 0.00 0.00 3.12 12:50:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 01:00:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 01:10:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 01:20:01 AM all 96.87 0.03 0.00 0.00 0.00 3.10 01:30:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 01:40:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 01:50:01 AM all 96.85 0.00 0.03 0.00 0.00 3.12 02:00:01 AM all 96.83 0.00 0.05 0.00 0.00 3.12 02:10:01 AM all 96.83 0.00 0.05 0.00 0.00 3.12 02:20:01 AM all 96.82 0.03 0.05 0.00 0.00 3.10 02:30:01 AM all 96.86 0.00 0.02 0.00 0.00 3.12 02:40:01 AM all 96.87 0.00 0.01 0.00 0.00 3.12 02:50:01 AM all 96.87 0.00 0.01 0.00 0.00 3.13 03:00:01 AM all 96.87 0.00 0.01 0.00 0.00 3.13 03:10:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 03:20:01 AM all 96.87 0.03 0.01 0.00 0.00 3.09 03:30:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 03:40:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 03:50:01 AM all 96.87 0.00 0.01 0.00 0.00 3.12 04:00:01 AM all 96.83 0.00 0.04 0.00 0.00 3.12 04:10:01 AM all 96.84 0.00 0.05 0.00 0.00 3.11 04:20:01 AM all 96.83 0.03 0.05 0.00 0.00 3.10 04:30:01 AM all 96.84 0.00 0.03 0.00 0.00 3.13 04:40:01 AM all 96.86 0.00 0.01 0.00 0.00 3.12 04:50:01 AM all 96.87 0.00 0.01 0.00 0.00 3.12 05:00:01 AM all 96.87 0.00 0.01 0.00 0.00 3.12 05:10:01 AM all 96.87 0.00 0.01 0.00 0.00 3.12 05:20:02 AM all 96.87 0.03 0.01 0.00 0.00 3.10 05:30:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 05:40:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 05:50:01 AM all 96.87 0.00 0.01 0.00 0.00 3.12 06:00:01 AM all 96.84 0.00 0.03 0.00 0.00 3.12 06:10:01 AM all 96.84 0.00 0.04 0.00 0.00 3.12 06:20:01 AM all 96.83 0.03 0.04 0.00 0.00 3.10 06:30:01 AM all 95.79 0.00 0.04 0.00 0.00 4.17 06:40:01 AM all 75.97 0.00 0.01 0.00 0.00 24.02 06:50:01 AM all 67.99 0.00 0.01 0.00 0.00 32.00 07:00:01 AM all 60.92 0.00 0.01 0.00 0.00 39.08 07:00:01 AM CPU %user %nice %system %iowait %steal %idle 07:10:01 AM all 53.25 0.00 0.01 0.00 0.00 46.74 07:20:01 AM all 53.12 0.03 0.01 0.00 0.00 46.84 07:30:01 AM all 52.93 0.00 0.01 0.00 0.00 47.07 07:40:01 AM all 48.30 0.00 0.01 0.00 0.00 51.70 07:50:01 AM all 46.87 0.00 0.01 0.00 0.00 53.12 08:00:01 AM all 45.76 0.00 0.01 0.00 0.00 54.23 08:10:01 AM all 43.73 0.00 0.02 0.00 0.00 56.25 08:20:01 AM all 42.54 0.03 0.02 0.00 0.00 57.41 08:30:01 AM all 35.41 0.00 0.02 0.00 0.00 64.57 08:40:01 AM all 17.18 0.00 0.01 0.00 0.00 82.81 08:50:01 AM all 1.34 0.00 0.00 0.00 0.00 98.66 09:00:01 AM all 0.00 0.00 0.00 0.00 0.00 100.00 09:10:01 AM all 11.84 0.00 0.05 0.00 0.00 88.12 09:20:01 AM all 96.87 0.03 0.01 0.00 0.00 3.10 09:30:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 09:40:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 09:50:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 10:00:02 AM all 96.87 0.00 0.00 0.00 0.00 3.12 10:10:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 10:20:01 AM all 96.87 0.03 0.01 0.00 0.00 3.10 10:30:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 10:40:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 10:50:01 AM all 72.11 0.00 0.08 0.00 0.00 27.82 11:00:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 11:10:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 11:20:01 AM all 96.87 0.03 0.01 0.00 0.00 3.10 11:30:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 11:40:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 11:50:01 AM all 96.87 0.00 0.00 0.00 0.00 3.12 12:00:01 PM all 96.87 0.00 0.00 0.00 0.00 3.12 12:10:01 PM all 96.87 0.00 0.00 0.00 0.00 3.12 12:20:01 PM all 96.87 0.03 0.01 0.00 0.00 3.10 12:30:01 PM all 96.81 0.00 0.06 0.00 0.00 3.12 12:40:01 PM all 96.83 0.00 0.05 0.00 0.00 3.12 12:50:01 PM all 96.82 0.00 0.05 0.00 0.00 3.12 01:00:01 PM all 96.84 0.00 0.04 0.00 0.00 3.12 01:10:01 PM all 96.87 0.00 0.00 0.00 0.00 3.12 01:20:01 PM all 96.87 0.00 0.00 0.00 0.00 3.12 01:30:01 PM all 96.87 0.00 0.00 0.00 0.00 3.12 01:40:01 PM all 96.87 0.00 0.00 0.00 0.00 3.12 Average: all 85.66 0.00 0.02 0.00 0.00 14.32 01:55:55 PM LINUX RESTART 02:00:01 PM CPU %user %nice %system %iowait %steal %idle 02:10:01 PM all 0.06 0.00 0.01 0.03 0.00 99.90 Average: all 0.06 0.00 0.01 0.03 0.00 99.90 02:17:13 PM LINUX RESTART
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Linux Performance Monitoring
3. Memory Free and Used (sar -r)
This reports the memory statistics. "1 3" reports for every 1 seconds a total of 3 times. Most likely you'll focus on "kbmemfree" and "kbmemused" for free and used memory.
$ sar -r 1 3 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 07:28:06 AM kbmemfree kbmemused %memused kbbuffers kbcached kbcommit %commit kbactive kbinact 07:28:07 AM 6209248 2097432 25.25 189024 1796544 141372 0.85 1921060 88204 07:28:08 AM 6209248 2097432 25.25 189024 1796544 141372 0.85 1921060 88204 07:28:09 AM 6209248 2097432 25.25 189024 1796544 141372 0.85 1921060 88204 Average: 6209248 2097432 25.25 189024 1796544 141372 0.85 1921060 88204Following are few variations:
4. Swap Space Used (sar -S)
- sar -r
- sar -r 1 3
- sar -r -f /var/log/sa/sa10
This reports the swap statistics. "1 3" reports for every 1 seconds a total of 3 times. If the "kbswpused" and "%swpused" are at 0, then your system is not swapping.
$ sar -S 1 3 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 07:31:06 AM kbswpfree kbswpused %swpused kbswpcad %swpcad 07:31:07 AM 8385920 0 0.00 0 0.00 07:31:08 AM 8385920 0 0.00 0 0.00 07:31:09 AM 8385920 0 0.00 0 0.00 Average: 8385920 0 0.00 0 0.00Following are few variations:
- sar -S
- sar -S 1 3
- sar -S -f /var/log/sa/sa10
Notes:
5. Overall I/O Activities (sar -b)
- Use "sar -R" to identify number of memory pages freed, used, and cached per second by the system.
- Use "sar -H" to identify the hugepages (in KB) that are used and available.
- Use "sar -B" to generate paging statistics. i.e Number of KB paged in (and out) from disk per second.
- Use "sar -W" to generate page swap statistics. i.e Page swap in (and out) per second.
This reports I/O statistics. "1 3" reports for every 1 seconds a total of 3 times.
Following fields are displays in the example below.
- tps Transactions per second (this includes both read and write)
- rtps Read transactions per second
- wtps Write transactions per second
- bread/s Bytes read per second
- bwrtn/s Bytes written per second
$ sar -b 1 3 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 01:56:28 PM tps rtps wtps bread/s bwrtn/s 01:56:29 PM 346.00 264.00 82.00 2208.00 768.00 01:56:30 PM 100.00 36.00 64.00 304.00 816.00 01:56:31 PM 282.83 32.32 250.51 258.59 2537.37 Average: 242.81 111.04 131.77 925.75 1369.90Following are few variations:
- sar -b
- sar -b 1 3
- sar -b -f /var/log/sa/sa10
Note: Use "sar -v" to display number of inode handlers, file handlers, and pseudo-terminals used by the system.
6. Individual Block Device I/O Activities (sar -d)To identify the activities by the individual block devices (i.e a specific mount point, or LUN, or partition), use "sar -d"
$ sar -d 1 1 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 01:59:45 PM DEV tps rd_sec/s wr_sec/s avgrq-sz avgqu-sz await svctm %util 01:59:46 PM dev8-0 1.01 0.00 0.00 0.00 0.00 4.00 1.00 0.10 01:59:46 PM dev8-1 1.01 0.00 0.00 0.00 0.00 4.00 1.00 0.10 01:59:46 PM dev120-64 3.03 64.65 0.00 21.33 0.03 9.33 5.33 1.62 01:59:46 PM dev120-65 3.03 64.65 0.00 21.33 0.03 9.33 5.33 1.62 01:59:46 PM dev120-0 8.08 0.00 105.05 13.00 0.00 0.38 0.38 0.30 01:59:46 PM dev120-1 8.08 0.00 105.05 13.00 0.00 0.38 0.38 0.30 01:59:46 PM dev120-96 1.01 8.08 0.00 8.00 0.01 9.00 9.00 0.91 01:59:46 PM dev120-97 1.01 8.08 0.00 8.00 0.01 9.00 9.00 0.91In the above example "DEV" indicates the specific block device.
For example: "dev53-1" means a block device with 53 as major number, and 1 as minor number.
The device name (DEV column) can display the actual device name (for example: sda, sda1, sdb1 etc.,), if you use the -p option (pretty print) as shown below.
$ sar -p -d 1 1 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 01:59:45 PM DEV tps rd_sec/s wr_sec/s avgrq-sz avgqu-sz await svctm %util 01:59:46 PM sda 1.01 0.00 0.00 0.00 0.00 4.00 1.00 0.10 01:59:46 PM sda1 1.01 0.00 0.00 0.00 0.00 4.00 1.00 0.10 01:59:46 PM sdb1 3.03 64.65 0.00 21.33 0.03 9.33 5.33 1.62 01:59:46 PM sdc1 3.03 64.65 0.00 21.33 0.03 9.33 5.33 1.62 01:59:46 PM sde1 8.08 0.00 105.05 13.00 0.00 0.38 0.38 0.30 01:59:46 PM sdf1 8.08 0.00 105.05 13.00 0.00 0.38 0.38 0.30 01:59:46 PM sda2 1.01 8.08 0.00 8.00 0.01 9.00 9.00 0.91 01:59:46 PM sdb2 1.01 8.08 0.00 8.00 0.01 9.00 9.00 0.91Following are few variations:
7. Display context switch per second (sar -w)
- sar -d
- sar -d 1 3
- sar -d -f /var/log/sa/sa10
- sar -p -d
This reports the total number of processes created per second, and total number of context switches per second. "1 3" reports for every 1 seconds a total of 3 times.
$ sar -w 1 3 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 08:32:24 AM proc/s cswch/s 08:32:25 AM 3.00 53.00 08:32:26 AM 4.00 61.39 08:32:27 AM 2.00 57.00Following are few variations:
8. Reports run queue and load average (sar -q)
- sar -w
- sar -w 1 3
- sar -w -f /var/log/sa/sa10
This reports the run queue size and load average of last 1 minute, 5 minutes, and 15 minutes. "1 3" reports for every 1 seconds a total of 3 times.
$ sar -q 1 3 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 06:28:53 AM runq-sz plist-sz ldavg-1 ldavg-5 ldavg-15 blocked 06:28:54 AM 0 230 2.00 3.00 5.00 0 06:28:55 AM 2 210 2.01 3.15 5.15 0 06:28:56 AM 2 230 2.12 3.12 5.12 0 Average: 3 230 3.12 3.12 5.12 0Note: The "blocked" column displays the number of tasks that are currently blocked and waiting for I/O operation to complete.
Following are few variations:
9. Report network statistics (sar -n)
- sar -q
- sar -q 1 3
- sar -q -f /var/log/sa/sa10
This reports various network statistics. For example: number of packets received (transmitted) through the network card, statistics of packet failure etc.,. "1 3" reports for every 1 seconds a total of 3 times.
sar -n KEYWORDKEYWORD can be one of the following:
- DEV Displays network devices vital statistics for eth0, eth1, etc.,
- EDEV Display network device failure statistics
- NFS Displays NFS client activities
- NFSD Displays NFS server activities
- SOCK Displays sockets in use for IPv4
- IP Displays IPv4 network traffic
- EIP Displays IPv4 network errors
- ICMP Displays ICMPv4 network traffic
- EICMP Displays ICMPv4 network errors
- TCP Displays TCPv4 network traffic
- ETCP Displays TCPv4 network errors
- UDP Displays UDPv4 network traffic
- SOCK6, IP6, EIP6, ICMP6, UDP6 are for IPv6
- ALL This displays all of the above information. The output will be very long.
$ sar -n DEV 1 1 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 01:11:13 PM IFACE rxpck/s txpck/s rxbyt/s txbyt/s rxcmp/s txcmp/s rxmcst/s 01:11:14 PM lo 0.00 0.00 0.00 0.00 0.00 0.00 0.00 01:11:14 PM eth0 342.57 342.57 93923.76 141773.27 0.00 0.00 0.00 01:11:14 PM eth1 0.00 0.00 0.00 0.00 0.00 0.00 0.0010. Report Sar Data Using Start Time (sar -s)When you view historic sar data from the /var/log/sa/saXX file using "sar -f" option, it displays all the sar data for that specific day starting from 12:00 a.m for that day.
Using "-s hh:mi:ss" option, you can specify the start time. For example, if you specify "sar -s 10:00:00", it will display the sar data starting from 10 a.m (instead of starting from midnight) as shown below.
You can combine -s option with other sar option.
For example, to report the load average on 26th of this month starting from 10 a.m in the morning, combine the -q and -s option as shown below.
$ sar -q -f /var/log/sa/sa23 -s 10:00:01 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 10:00:01 AM runq-sz plist-sz ldavg-1 ldavg-5 ldavg-15 blocked 10:10:01 AM 0 127 2.00 3.00 5.00 0 10:20:01 AM 0 127 2.00 3.00 5.00 0 ... 11:20:01 AM 0 127 5.00 3.00 3.00 0 12:00:01 PM 0 127 4.00 2.00 1.00 0There is no option to limit the end-time. You just have to get creative and use head command as shown below.
For example, starting from 10 a.m, if you want to see 7 entries, you have to pipe the above output to "head -n 10".
$ sar -q -f /var/log/sa/sa23 -s 10:00:01 | head -n 10 Linux 2.6.18-194.el5PAE (dev-db) 03/26/2011 _i686_ (8 CPU) 10:00:01 AM runq-sz plist-sz ldavg-1 ldavg-5 ldavg-15 blocked 10:10:01 AM 0 127 2.00 3.00 5.00 0 10:20:01 AM 0 127 2.00 3.00 5.00 0 10:30:01 AM 0 127 3.00 5.00 2.00 0 10:40:01 AM 0 127 4.00 2.00 1.00 2 10:50:01 AM 0 127 3.00 5.00 5.00 0 11:00:01 AM 0 127 2.00 1.00 6.00 0 11:10:01 AM 0 127 1.00 3.00 7.00 2There is lot more to cover in Linux performance monitoring and tuning. We are only getting started. More articles to come in the performance series.
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Display CPU Statistics using Sar Command
# sar u
Linux 2.6.9-42.ELsmp (dev-db) 01/01/2009
12:00:01 AM CPU %user %nice %system %iowait %idle
12:05:01 AM all 3.70 0.00 0.85 0.00 95.45
12:10:01 AM all 4.59 0.00 1.19 0.06 94.16
12:15:01 AM all 3.90 0.00 0.95 0.04 95.11
12:20:01 AM all 4.06 0.00 1.00 0.01 94.93
12:25:01 AM all 3.89 0.00 0.87 0.00 95.23
12:30:01 AM all 3.89 0.00 0.87 0.00 95.23
Skipped..
Average: all 4.56 0.00 1.00 0.15 94.29
Note:
If you need a break down of the performance data for the individual CPU's, execute the following command.# sar -u -P ALL
Display Disk IO Statistics using sar command
# sar d
Linux 2.6.9-42.ELsmp (dev-db) 01/01/2009
12:00:01 AM DEV tps rd_sec/s wr_sec/s
12:05:01 AM dev2-0 1.65 1.28 45.43
12:10:01 AM dev8-1 4.08 8.11 21.81
Skipped..
Average: dev2-0 4.66 120.77 69.45
Average: dev8-1 1.89 3.17 8.02
Display networking Statistics using sar command
# sar -n DEV | more
Linux 2.6.9-42.ELsmp (dev-db) 01/01/2009
12:00:01 AM IFACE rxpck/s txpck/s rxbyt/s txbyt/s rxcmp/s txcmp/
s rxmcst/s
12:05:01 AM lo 0.17 0.16 25.31 23.33 0.00 0.0
0 0.00
12:10:01 AM eth0 52.92 53.64 10169.74 12178.57 0.00 0.0
0 0.00
# sar -n SOCK |more
Linux 2.6.9-42.ELsmp (dev-db) 01/01/2009
12:00:01 AM totsck tcpsck udpsck rawsck ip-frag
12:05:01 AM 50 13 3 0 0
12:10:01 AM 50 13 4 0 0
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March 20, 2006
Sadc (system activity data collector) is the program that gathers performance data. It pulls its data out of the virtual /proc filesystem, then it saves the data in a file (one per day) named /var/log/sa/saDD where DD is the day of the month.Two shell scripts from the sysstat package control how the data collector is run. The first script, sa1, controls how often data is collected, while sa2 creates summary reports (one per day) in /var/log/sa/sarDD. Both scripts are run from cron. In the default configuration, data is collected every 10 minutes and summarized just before midnight.
If you suspect a performance problem with a particular program, you can use
sadcto collect data on a particular process (with the-xargument), or its children (-X), but you will need to set up a custom script using those flags.As Dr. Heisenberg showed, the act of measuring something changes it. Any tool that collects performance data has some overall negative impact on system performance, but with sar, the impact seems to be minimal. I ran a test with the sa1 cron job set to gather data every minute (on a server that was not busy) and it didn't cause any serious issues. That may not hold true on a busy system.
Creating reports
If the daily summary reports created by the sa2 script are not enough, you can create your own custom reports using sar. The sar program reads data from the current daily data file unless you specify otherwise. To have sar read a particular data file, use the
-f /var/log/sa/saDDoption. You can select multiple files by using multiple-foptions. Since many of sar's reports are lengthy, you may want to pipe the output to a file.To create a basic report showing CPU usage and I/O wait time percentage, use
sarwith no flags. It produces a report similar to this:01:10:00 PM CPU %user %nice %system %iowait %idle 01:20:00 PM all 7.78 0.00 3.34 20.94 67.94 01:30:00 PM all 0.75 0.00 0.46 1.71 97.08 01:40:00 PM all 0.65 0.00 0.48 1.63 97.23 01:50:00 PM all 0.96 0.00 0.74 2.10 96.19 02:00:00 PM all 0.58 0.00 0.54 1.87 97.01 02:10:00 PM all 0.80 0.00 0.60 1.27 97.33 02:20:01 PM all 0.52 0.00 0.37 1.17 97.94 02:30:00 PM all 0.49 0.00 0.27 1.18 98.06 Average: all 1.85 0.00 0.44 2.56 95.14If the %idle is near zero, your CPU is overloaded. If the %iowait is large, your disks are overloaded.
To check the kernel's paging performance, use
sar -B, which will produce a report similar to this:11:00:00 AM pgpgin/s pgpgout/s fault/s majflt/s 11:10:00 AM 8.90 34.08 0.00 0.00 11:20:00 AM 2.65 26.63 0.00 0.00 11:30:00 AM 1.91 34.92 0.00 0.00 11:40:01 AM 0.26 36.78 0.00 0.00 11:50:00 AM 0.53 32.94 0.00 0.00 12:00:00 PM 0.17 30.70 0.00 0.00 12:10:00 PM 1.22 27.89 0.00 0.00 12:20:00 PM 4.11 133.48 0.00 0.00 12:30:00 PM 0.41 31.31 0.00 0.00 Average: 130.91 27.04 0.00 0.00Raw paging numbers may not be of concern, but a high number of major faults (majflt/s) indicate that the system needs more memory. Note that majflt/s is only valid with kernel versions 2.5 and later.
For network statistics, use
sar -n DEV. The-n DEVoption tells sar to generate a report that shows the number of packets and bytes sent and received for each interface. Here is an abbreviated version of the report:11:00:00 AM IFACE rxpck/s txpck/s rxbyt/s txbyt/s 11:10:00 AM lo 0.62 0.62 35.03 35.03 11:10:00 AM eth0 29.16 36.71 4159.66 34309.79 11:10:00 AM eth1 0.00 0.00 0.00 0.00 11:20:00 AM lo 0.29 0.29 15.85 15.85 11:20:00 AM eth0 25.52 32.08 3535.10 29638.15 11:20:00 AM eth1 0.00 0.00 0.00 0.00To see network errors, try
sar -n EDEV, which shows network failures.Reports on current activity
Sar can also be used to view what is happening with a specific subsystem, such as networking or I/O, almost in real time. By passing a time interval (in seconds) and a count for the number of reports to produce, you can take an immediate snapshot of a system to find a potential bottleneck.
For example, to see the basic report every second for the next 10 seconds, use
sar 1 10. You can run any of the reports this way to see near real-time results.Benchmarking
Even if you have plenty of horsepower to run your applications, you can use sar to track changes in the workload over time. To do this, save the summary reports (sar only saves seven) to a different directory over a period of a few weeks or a month. This set of reports can serve as a baseline for the normal system workload. Then compare new reports against the baseline to see how the workload is changing over time. You can automate your comparison reports with AWK or your favorite programming language.
In large systems management, benchmarking is important to predict when and how hardware should be upgraded. It also provides ammunition to justify your hardware upgrade requests.
Digging deeper
In my experience, most hardware performance problems are related to the disks, memory, or CPU. Perhaps more frequently, application programming errors or poorly designed databases cause serious performance issues.
Whatever the problems, sar and friends can give you a comprehensive view of how things are working and help track down bottlenecks to fix a sluggish system. The examples here just scratch the surface of what sar can do. If you take a look at the man pages, it should be easy to customize a set of reports for your needs.
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Society
Groupthink : Two Party System as Polyarchy : Corruption of Regulators : Bureaucracies : Understanding Micromanagers and Control Freaks : Toxic Managers : Harvard Mafia : Diplomatic Communication : Surviving a Bad Performance Review : Insufficient Retirement Funds as Immanent Problem of Neoliberal Regime : PseudoScience : Who Rules America : Neoliberalism : The Iron Law of Oligarchy : Libertarian Philosophy
Quotes
War and Peace : Skeptical Finance : John Kenneth Galbraith :Talleyrand : Oscar Wilde : Otto Von Bismarck : Keynes : George Carlin : Skeptics : Propaganda : SE quotes : Language Design and Programming Quotes : Random IT-related quotes : Somerset Maugham : Marcus Aurelius : Kurt Vonnegut : Eric Hoffer : Winston Churchill : Napoleon Bonaparte : Ambrose Bierce : Bernard Shaw : Mark Twain Quotes
Bulletin:
Vol 25, No.12 (December, 2013) Rational Fools vs. Efficient Crooks The efficient markets hypothesis : Political Skeptic Bulletin, 2013 : Unemployment Bulletin, 2010 : Vol 23, No.10 (October, 2011) An observation about corporate security departments : Slightly Skeptical Euromaydan Chronicles, June 2014 : Greenspan legacy bulletin, 2008 : Vol 25, No.10 (October, 2013) Cryptolocker Trojan (Win32/Crilock.A) : Vol 25, No.08 (August, 2013) Cloud providers as intelligence collection hubs : Financial Humor Bulletin, 2010 : Inequality Bulletin, 2009 : Financial Humor Bulletin, 2008 : Copyleft Problems Bulletin, 2004 : Financial Humor Bulletin, 2011 : Energy Bulletin, 2010 : Malware Protection Bulletin, 2010 : Vol 26, No.1 (January, 2013) Object-Oriented Cult : Political Skeptic Bulletin, 2011 : Vol 23, No.11 (November, 2011) Softpanorama classification of sysadmin horror stories : Vol 25, No.05 (May, 2013) Corporate bullshit as a communication method : Vol 25, No.06 (June, 2013) A Note on the Relationship of Brooks Law and Conway Law
History:
Fifty glorious years (1950-2000): the triumph of the US computer engineering : Donald Knuth : TAoCP and its Influence of Computer Science : Richard Stallman : Linus Torvalds : Larry Wall : John K. Ousterhout : CTSS : Multix OS Unix History : Unix shell history : VI editor : History of pipes concept : Solaris : MS DOS : Programming Languages History : PL/1 : Simula 67 : C : History of GCC development : Scripting Languages : Perl history : OS History : Mail : DNS : SSH : CPU Instruction Sets : SPARC systems 1987-2006 : Norton Commander : Norton Utilities : Norton Ghost : Frontpage history : Malware Defense History : GNU Screen : OSS early history
Classic books:
The Peter Principle : Parkinson Law : 1984 : The Mythical Man-Month : How to Solve It by George Polya : The Art of Computer Programming : The Elements of Programming Style : The Unix Haters Handbook : The Jargon file : The True Believer : Programming Pearls : The Good Soldier Svejk : The Power Elite
Most popular humor pages:
Manifest of the Softpanorama IT Slacker Society : Ten Commandments of the IT Slackers Society : Computer Humor Collection : BSD Logo Story : The Cuckoo's Egg : IT Slang : C++ Humor : ARE YOU A BBS ADDICT? : The Perl Purity Test : Object oriented programmers of all nations : Financial Humor : Financial Humor Bulletin, 2008 : Financial Humor Bulletin, 2010 : The Most Comprehensive Collection of Editor-related Humor : Programming Language Humor : Goldman Sachs related humor : Greenspan humor : C Humor : Scripting Humor : Real Programmers Humor : Web Humor : GPL-related Humor : OFM Humor : Politically Incorrect Humor : IDS Humor : "Linux Sucks" Humor : Russian Musical Humor : Best Russian Programmer Humor : Microsoft plans to buy Catholic Church : Richard Stallman Related Humor : Admin Humor : Perl-related Humor : Linus Torvalds Related humor : PseudoScience Related Humor : Networking Humor : Shell Humor : Financial Humor Bulletin, 2011 : Financial Humor Bulletin, 2012 : Financial Humor Bulletin, 2013 : Java Humor : Software Engineering Humor : Sun Solaris Related Humor : Education Humor : IBM Humor : Assembler-related Humor : VIM Humor : Computer Viruses Humor : Bright tomorrow is rescheduled to a day after tomorrow : Classic Computer Humor
The Last but not Least Technology is dominated by two types of people: those who understand what they do not manage and those who manage what they do not understand ~Archibald Putt. Ph.D
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Last modified: March, 12, 2019
