Posts Tagged 'iostat'

Analyzing IO at the Exadata Cell level… iostat summary

While analyzing Write-Back cache activity on Exadata storage cells, I wanted something to interactively monitor IO while I was running various tests.  The problem is summarizing the results from ALL storage cell.  So, I decided to use my old friend “iostat” and a quick easy script to roll up the results for both DISK and FLASH.  This allowed me to monitor the IOPS, IO size, wait times, and service times.  

The “iostat-all.sh” tool shows the following data:

day           time  device  r      w   rs       ws     ss    aw    st
---------------------------------------------------------------------
 2013-06-24 14:40:11 DISK  47  40252   54  2667941  66.15  0.28  0.07
 2013-06-24 14:40:11 FLASH  9  40354  322  2853674  70.70  0.13  0.13
 2013-06-24 14:41:13 DISK  48  39548   80  2691362  67.95  0.31  0.08
 2013-06-24 14:41:13 FLASH  9  53677  324  3975687  74.06  0.14  0.13
…

Hopefully this will be useful for those that like to dive into the weeds using our good old friends.

Solaris Eye for the Linux guy… or how I learned to stop worrying about Linux and Love Solaris (Part 1)

This entry goes out to my Oracle techie friends that have been in the Linux camp for sometime now and are suddenly finding themselves needing to know more about Solaris… hmmmm… I wonder if this has anything to do with Solaris now being an available option with Exadata?  Or maybe the recent announcement that the SPARC T3 multiplier for T3-x servers is now 0.25.  Judging by my inbox recently, I suspect a renewed interest in Solaris to continue.

I have focused on Oracle database performance on Solaris for 14 years now.  In the last few years, I began to work on Exadata and found myself  needing to learn the “Linux” way of performance analysis.   I will cover some basic tools needed for Oracle performance analysis with Solaris as well as some special performance topics.  I am not a deep dive kernel type of guy, so don’t expect esoteric Dtrace scripts to impress your friends.  I am not going to cover how to patch and maintain Solaris – this is out of scope. With this in mind, lets get started.

prstat(1M) … top on steriods!

Probably the first tool that the typical Linux performance guy reaches for is top.  This is part of every Linux distribution that I know of but is sadly missing from Solaris… But Solaris has something much better “prstat(1m)“.  I know the name is boring but it simply means “process status”.  This is the first place to get an idea of how processes are performing on a system and quite likely the most useful tool in general.

# prstat
PID USERNAME  SIZE   RSS STATE  PRI NICE      TIME  CPU PROCESS/NLWP      
 5623 oracle     32G   32G cpu63    0    0   0:02:23 1.0% oracle/1
 5625 oracle     32G   32G cpu60    0    0   0:02:22 1.0% oracle/1
 5627 oracle     32G   32G sleep    0    0   0:02:18 1.0% oracle/1
 5629 oracle     32G   32G cpu38    0    0   0:02:16 1.0% oracle/1
 5609 oracle     43M   38M sleep    0    4   0:01:21 0.6% rwdoit/1
 5605 oracle     43M   38M sleep    0    4   0:01:18 0.6% rwdoit/1
 5607 oracle     43M   38M sleep    0    4   0:01:18 0.6% rwdoit/1
 5601 oracle     43M   38M sleep    0    4   0:01:17 0.6% rwdoit/1
...
...
Total: 106 processes, 447 lwps, load averages: 5.03, 7.11, 19.48

Top would show you....

# top
load averages:  5.06,  6.84, 18.81                                                                             14:50:13
109 processes: 100 sleeping, 1 stopped, 8 on cpu
CPU states: 92.7% idle,  4.0% user,  3.3% kernel,  0.0% iowait,  0.0% swap
Memory: 128G real, 60G free, 50G swap in use, 135G swap free

 PID USERNAME THR PRI NICE  SIZE   RES STATE   TIME CPU-a- COMMAND
 5623 oracle     1   0    0    0K    0K cpu57   3:08 66.41% oracle
 5625 oracle     1   0    0    0K    0K cpu33   3:06 66.02% oracle
 5627 oracle     1   0    0    0K    0K cpu14   3:02 64.45% oracle
 5629 oracle     1   0    0    0K    0K cpu41   2:59 63.28% oracle
 5609 oracle     1   0    4    0K    0K cpu31   1:46 37.70% rwdoit
 5605 oracle     1   0    4    0K    0K cpu55   1:43 36.33% rwdoit
 5607 oracle     1   0    4    0K    0K sleep   1:43 36.33% rwdoit
 5601 oracle     1   0    4    0K    0K cpu32   1:42 35.94% rwdoit

What is happening?  “top” shows details from a from process point of view where as by default prstat(1M) shows the system aggregates.  To make prstat(1M) look more like top, you have to enable micro-state accounting with the “-m” option.  With the “-m” option, prstat(1M) shows CPU utilization of various processes like top but with a LOT more detail.  You have access to details regarding CPU time broken out by user and system.  You can find out the percentage of time spent in traps, sleep, and time spent waiting for CPU “LAT”.  Finally, you can see the number of voluntary and involuntary context switches along with the number of threads per process.

# prstat -m
PID USERNAME USR SYS TRP TFL DFL LCK SLP LAT VCX ICX SCL SIG PROCESS/NLWP 
 5623 oracle    48  18 0.0 0.0 0.0 0.0  29 4.3 38K   8 .3M   0 oracle/1
 5625 oracle    48  18 0.0 0.0 0.0 0.0  30 4.3 38K   9 .3M   0 oracle/1
 5627 oracle    43  21 0.0 0.0 0.0 0.0  30 5.5 32K   7 .3M   0 oracle/1
 5629 oracle    42  21 0.0 0.0 0.0 0.0  31 5.6 33K   6 .3M   0 oracle/1
 5609 oracle    17  21 0.0 0.0 0.0 0.0  57 5.7 33K   5 77K   0 rwdoit/1
 5605 oracle    20  17 0.0 0.0 0.0 0.0  59 4.5 38K   5 89K   0 rwdoit/1
 5607 oracle    17  19 0.0 0.0 0.0 0.0  58 5.4 32K   4 75K   0 rwdoit/1
 5601 oracle    20  16 0.0 0.0 0.0 0.0  59 4.5 38K   5 90K   0 rwdoit/1

There are a lot of options available to prstat(1M) so do take a look at the prstat(1M) man page. Also look at the “scalingbits” blog for an excellent discussion on prstat(1M) monitoring.  Stephan goes into much more detail about the utility and how to monitor by “zones” or “projects”… very useful stuff.

lsof = pfiles(1M)… the proc(1) commands

pfiles(1M) mirrors what “lsof” does but there is much more information available on a per-process basis available.  A man of “proc(1)” shows the available process related commands: “pstack(1M)”, “pldd(1M)”, and “pflags(1M) to name a few.  These utilities referred to as process introspection commands are detailed nicely on the solarisinternals.com website.

vmstat(1M), mpstat(1M), iostat(1M), sar(1M)… basically the same!

It is good to know that somethings are not all that different.  The above tools have minor differences, but generally look the same.  Some options are different and expanded.   Take for example iostat.

“iostat(1M) for Solaris has as a “z” option that takes out the devices that are not doing any IO and have “Zeros”.  The biggest issue with most of these tools come into play when there are missing options or the formatting is different.  This messes up scripts that have been developed to help aid analysis.  This is not too hard to fix… just something that is going to have to be worked out.

References

The best references for Solaris performance and analysis would be the “Solaris Internals” and the “Solaris Performance and Tools” books.  These books describe the architecture of Solaris and show how to analyze and diagnosis performance issues… and you can get them on the kindle 🙂  The books also have an accompanying website “solarisinternals.com” to continue the discussion.

That is all for now…