EVA8400 is advertised as an active-active (AA) storage – a LUN can be accessed via both controllers. But if you look at the small letters you will see that it is actually asymmetric AA storage (AAA), which is a cheaper class of AA storages. While all LUNs can still be accessed via both controllers, LUNs still have owning controller. If I/O request comes to a non-owning controller it will be transfered to the owner and only then performed. This of course has impact on the performance. To avoid this EVA monitors the requests, and if more than 60% of requests are coming through non-owning controller ownership is changed.

Preferred method of access for AAA storages is using asymmetric logical unit access (ALUA) – method that enables target (storage system) to set different access characteristics to different paths based on the owning controller (this is known as target port group support (TPGS)). For example, if Controller_A owns LUN_1, all paths for LUN_1 to Controller_A will be marked as Active/Optimized, while all paths to Controller_B will be marked as Active/NonOptimized.

Knowing all this, it is only obvious that ideal setup for AAA storages is when one half of LUNs is owned by one controller and the other half by second controller. This enables us to balance the load on both controllers and get the maximum performance out of the storage.

Now, on the client side some systems have Veritas suite installed, but there are a couple of servers that are using Solaris native MPxIO as a multipathing solution. By specification MPxIO is ALUA aware plus it comes with a nice feature to balance the traffic across all Active paths. EVA8400 controllers have 4 x 4Gbps fibre channel ports each, while my servers have 2 x 8Gbps HBAs. Spreading the traffic across all 4 target ports would help me get needed performance.

Everything sounds perfect in theory, but I’m having problems to make this work in practice. For some reason MPxIO does all the I/O over Controller A and, since with MPxIO path priority can not be set manually, after a while all LUNs are moved to this controller leaving second controller idle. Since TPGS specification is vendor specific there seems to be some incompatibility between HP and Sun implementation. Or maybe there are some hidden undocumented options that have to be set – so far I had no luck in finding these. :-/

During the tests and in order to see how the LUNs were spread I wrote a script that counts Active paths per target port. Maybe someone else will find it useful. Download can be found here. And here is how it looks in action:

root@xdb1-ora:~# get_san_paths.py
Initiator ports found:    2
Target ports found:       8
LUNs found:              87
 
Path \ LUNs:
  50001fe150229f78: 77 LUNs
  50001fe150229f79: 77 LUNs
  50001fe150229f7c: 10 LUNs
  50001fe150229f7d: 10 LUNs
  50001fe150229f7a: 77 LUNs
  50001fe150229f7b: 77 LUNs
  50001fe150229f7e: 10 LUNs
  50001fe150229f7f: 10 LUNs

Non-verbose mode:

$ ./svc_lsmigrate.py -H svccluster
# (ID  ) Vdisk         Size      (ID ) Mdisk Group    Threads Progress
======================================================================
1 (67  ) esx_srvf05_d  1000.00GB (8  ) DS482_5r10_SK1 1       48 %
2 (157 ) esx_srvf06_g  1000.00GB (5  ) DS483_8r5_2SK3 1       96 %
3 (118 ) esx_srvf01_h  1022.00GB (1  ) DS482_8r5_SK3  1       63 %
4 (117 ) esx_srvf01_g     1.00TB (1  ) DS482_8r5_SK3  1       63 %
5 (120 ) esx_srvf01_i  1023.00GB (1  ) DS482_8r5_SK3  1       63 %
6 (39  ) tsm_disk4        5.00GB (10 ) DS484_9r5_1SK2 1       98 %
7 (19  ) oracode_tunis  800.00GB (5  ) DS483_8r5_2SK3 1       59 %

If you find the script useful, you can download it here.

Note: in order for script to work, you need to have SVC connection parameters set in your SSH config file. Example could be:

$ grep -p svccluster ~/.ssh/config
Host svccluster
  Hostname 192.168.1.34
  User admin
  IdentityFile ~/.ssh/admin.key

Note #2: Script was tested on SVC software levels 4.3 and 5.1.

Main news is that now it is possible to change Pidgin status message periodically. Script will go to background (it is a real daemon now :P), change the status, and wait for the set time interval until it changes the message again, and then all over again, wait-change-wait-change.

To change status message every 5 minutes with a random line from file /home/miljan/quotes/dusko_radovic.txt:

pidgin_status.py -d -t 5 -f /home/miljan/quote/dusko_radovic.txt

And in Pidgin you would get something like this every five minutes:

To show the song you are listening to as status message:

pidgin_status.py -s “Mukeka di Rato – Kustapassaaessedrmobral”

And in Pidgin it would look like:

You can see all possible options by running script with -h argument for help.

bleketux, I hope you are still around to enjoy this. ;)

Download: pidgin_status_v2.py

To cut the long story short, I needed something that will update my Pidgin status message with the information about the current song I am listening. Till recently I was using Rhythmbox player and there is a perfect little Pidgin plugin called Current Track that worked with this player. Last week I discovered gmusicbrowser and fell in love immediately. It is fast, rich with functionalities but still simple to use. Exactly what I want from audio player. (Hm, I just noticed it is written in PERL. Now when Python is used for everything this comes as a big surprise.)

gmusicbrowser already has a plugin called NowPlaying. It will trigger some command whenever song is changed. I just needed to write this command that will inform Pidgin about the change. So, this seemed like a perfect exercise for slow Saturday. :)

Quick search on Pidgin and D-BUS showed extensive documentation about Pidgin API accessible through D-BUS. There is even a working example of how to change the status message! :)

But that was too simple, so I got another idea. Some time ago, I wrote a small daemon in C that will bind to a specific port and display random bofh-excuses fortune messages when someone would telnet to it. (Seems like I have a lot of spare time. I should really find some hobby!) Something similar to telnet bofh.jeffballard.us 666 (here for more information). So I was thinking about implementing the same for my Pidgin status. Random BOFH excuses in your status message! How cool geeky is that!

The result of all that is short (~60 lines of code) Python script that will set your Pidgin status message to:

a) you current song

pidgin_status.py -m The Real McKenzies – Outta Scotch

b) random line from a file

pidgin_status.py -f /usr/local/share/bofh-example

c) anything you give as the command line argument

pidgin_status.py Some very interesting and funny status message

Only difference between a) and c) is the type of the icon that will be shown. In example a) there will be a small musical note, while in example b) and c) nice arrow pointing to right side will be show.

In the middle of testing I noticed this strange message:

Being from Serbia myself, I find this extremely funny. Although, I didn’t know Serbian hackers are so notorious! :)

I hope someone will find it useful. In any case, I am accepting donations for some long and adventurous vacation. As you can see, I really need it! :D

pidgin_status.py
bofh-excuses