Samstag Mai 24, 2014

Checking VXFS QIO usage

This isn't something new however given that i saw this problem at a customer just last week, i would like to point to something you have to keep in mind when using Oracle DB with the Veritas Filesystem.

When you have strange performance problem when using VXFS please ensure that the database isn't sitting around in the POSIX inode r/w-lock with it's database writes. Check if Quick-I/O (solves the issue) or ODM (solves the issue as well) is really activated. QIO is not activated by just using the FILESYSTEMIO_OPTION=setall or by mounting the filesystem with the mount option qio. You have to do more and it looks like this is sometimes forgotten by people setting up or migrating a system.


Creating a zpool configuration out of a bunch of F40/80 cards

In a some customer situation i'm using a number of Oracle Sun Flash Accelerator F40 PCIe Cards or F80 PCIe cards to create flash storage areas inside a server. For example i had 8 F40 cards in a server by using a SPARC M10 and a PCIe Expansion Box which enables you to connect up to 11 F40/F40 cards per expansion box.

The configuration with 8 F80 cards for example is a configuration i'm using on very special occasions and for special purposes, in this case it was a self-written application of a customer needing a lot flash storage inside the server. I won't disclose more. On the other side: I'm sizing quite frequently systems with two F80 cards for "separated ZIL" purposes . Either if you use the SSD as data storage or as separated ZIL: When you do mirroring you have to ensure that mirrors are not using mirror halves on the same card.

From the systems perspective you see four disk devices per F40/F80 card with 100 respective 200 GB capacity per disk and thus you can just add them to your zpool configuration. However configuring the system was a little bit unpractical. The problem: It's not that easy to create a configuration that ensures that no mirror has it's two vdevs on a single F40/F80 card. Perhaps there is an easier way, however I didn't found it so far.

It's a little bit hard to find acceptable disk pairs when you are looking on PCI trees like /devices/pci@8000/pci@4/pci@0/pci@8/pci@0/pci@0/pci@0/pci@1/pci@0/pci@1/pciex1000,7e@0/iport@80:scsi. Well, at two cards it's not that hard, but still not a nice job. After doing this manually a few times, i thought that at 8 or 22 cards doing this manually is a job for people who killed baby seals, listen to Justin Bieber or equivalent horrible things.

But i didn't committed to such crimes and this problem is nothing that a little bit of shell-fu can't solve. You can do it in a single line of shell. Well ... a kind of a single line of shell.


Montag Aug 26, 2013

Less known Solaris 11.1 features: A user in 1024 groups and a workaround for a 25 year old problem

For a long time the maximum number of groups a user could belong to was 16, albeit there was a way to get 32. In Solaris 11 and recent versions of Solaris 10, the maximum number of groups a user could belong to is 1024 (which is the same limit Windows sets in this regard). It's easy to set the new limit.

set ngroups_max=1024
After a reboot, this change will be active. But why isn't this the default? There are good reasons for it. I will show you one of them in this entry. Like thinking that two digits for the year or using a signed 32-bit integer for storing the system time, the issue has it's root cause in a decision made a long time ago … in this example the moment in the past is at least 25 years ago. And often just changing something, breaks stuff that is really old, but still in use.

Experienced Solaris users, who tuned their Solaris System for up to 32 groups per user, already know the component that will be broken by having more than 16 users, because a message at the next boot of the system after the change in /etc/system that next startup will deliver a warning.

However, as i already said, there is a a solution for this problem since Solaris 11.1. This blog entry will show the workaround in action.

(read more)

Montag Aug 19, 2013

Less known Solaris features: pfedit - editing is not everything

You have allowed junior to edit the httpd.conf and you are capable to monitor the changes with pfedit. However there is a little problem. She or he can't restart the apache demon to make the new config active. When junior tries to restart the service, he or she just gets a "permission denied".


Less known Solaris 11.1 features: Auditing pfedit usage

You have allowed junior to edit the httpd.conf and and some nice evening, you are sitting at home. Then: You get alerts on your mobile: Webserver down. You log into the server. You check the httpd.conf. You see an error. You correct it. You look into the change log. Nothing. You ask your colleagues, who made this change. Nobody. Dang. As always. Classic "Whodunit".

Okay, in order to prevent this for future changes, you want to record this kind of information. And working with pfedit is really useful in order to do so.


Less known Solaris 11.1 features: pfedit

It's a really nifty feature: Let's assume, you have a config file in your system and you want to allow your junior fellow admin to edit it from time to time, but don't want him to pass any further rights to him, because this machine is too important.

Solaris 11.1 has an interesting feature to delegate the privilege to edit just a file. The tool enabling this is called pfedit.

Read more at ....

Freitag Mrz 15, 2013


Brendan Gregg has written an interesting piece about finding performance problems: "The USE method addresses shortcomings in other commonly used methodologies".

It's a good paper, however ... well let's say, I don't understand why so many people find it especially cool or especially good, because at the end it isn't something really new. Don't understand me wrong: It's good. But not extraordinarily good. Like many methodologies it's basically just codified common sense with a personal spin. So I would prefer to say "My-personal-way-of-doing-stuff" instead of calling it methodology. There is nothing new in it. Just a lot of common sense.

I really think that performance analysis is not so much about a "methodology" you can simply follow that will lead you magically to a result. It's about a mindset how to tackle problems, it's about being structured in the approach, it's about "being prepared", it's a lot about knowing stuff.

As I do performance analysis quite frequently, I have created my own "methodology", or to be more correct ... my own mindset of doing such stuff. I don't call it method or methodologies. Perhaps it's useful for some or the other ... so i write it down here.

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Dienstag Jun 22, 2010


At the moment the RSS feed of isn't part of the frontpage aggregation and thus not part of the It you have read my blog via this feed in the past, i kindly ask you to subscribe directly to the feed of my blog at Feedburner. I want to apologize for any inconvenience.

Freitag Okt 26, 2007

Synchronisation deactivated

As you may have observed, this blog wasn´t updated for quite a while, as it was automatically feeded by my primary blog. I still work on a new gateway functionality for Serendipity to Roller, but this will be a task for my next vacation. So .. in case you found this blog interesting, please look at in the case you wasn´t redirected automatically.

Sonntag Aug 26, 2007


I finally found a good use for Twitter: I will use it as a scratchpad for links or snippets and a place for links that don´t justify an own blog entry or the addition to delicious. You will find the twitter-box on the right side at the top of the page.

Freitag Aug 24, 2007

T2 licensing for IBM software

IBM announced the PVU for the UltraSPARC T2 a few days ago: Processor Value Unit Licensing for Distributed SW. An UltraSPARC T2 counts as 50 PVUs. That´s really good news. Why? Well, wait for the benchmarks and do the math yourself ;)

BTW: The nice thing at PVUs: they have a political component. Thus PVUs are not really based of the real perfomance, they are based on the performance, IBM wants to admit. So, even when they don´t admit that T2 is better than Power6, they help us by making their software cheaper, and they can´t make them more expensive, as this would hurt their hardware bussiness by admiting, that T2 is better then Power6. Sometimes Catch-22´s are really funny ...

On the way to volume!

We fastly ramping up UltraSPARC T2. Here you see: 12 E10000k, only a little bit short of a quarter Terabit per second networkbandwith, 0,75 Terabyte per second memory bandwith, 96 cores, 192 integer pipelines, 96 crypro accelerators, 96 floating point units, 768 threads, 768 virtual processor. Imagine this processors in some nifty boxes, with a nice silver finish, 1 or 2 rack units high. Consuming only 1200 Watts for the processors. Imagine the load this babies can handle. 5 years ago, you had to fill a complete datacenter for a similar performance. Now it´s a small tray of CPUs (respective 12 or 24 rack units). Simply mind-boggling. But it´s even getting better: In the near future you will have this sheer power in only three machines.

Ein Vierteljahrhundert Compact Disc

Vor einigen Tagen ist die CD 25 alt geworden. Ich wollte eigentlich einen launigen Text dazu schreiben. Aber ich habe da ein Problem: Ich versuche mich gerade zu erinnern, welche CD denn meine erste war. An meine erste selbstgekaufte Platte kann mich noch gut erinnern: Appetite for Destruction von den Guns n´ Roses. Das Cover mit dem Mädel mit der halb runtergezogenen Damenunterbekleidung.

Ich kann mich sogar noch an meinen ersten CD-Player erinnern. Pioneer mit dem Stable Platter Mechanismus. Der dazu fuehrte, das ich beim lauschigen Ausklang eines Dates vor der Stereoanlage des öfteren den Player zur Herausgabe der CD zwingen musste, um sie erst mal umdrehen. Denkt man ja auch nicht dran, das die CD vielleicht mit der silbernen Seite nach oben muss. 1993 habe ich den gekauft ... irgendwann um den Dreh. Deswegen habe ich so einige ganz dunkele Vermutungen, welche CD denn von mir als erste erwählt worden ist.. Von den Dingen, die ich damals gehoert habe ist nur Peter Gabriel geblieben, und das ist auch gut so, zum einen weil Peter einfach der Meister ist, und der Rest wirklich schlecht war ..

Aber mir will einfach nicht einfallen, von wem die erste CD war. Ich hoffe gerade inständig, das es nicht Seal war ... obwohl er damals nicht ansatzweise der Schwiegermutterliebling von heute war ...

Aber das sich nicht erinnern können passt vielleicht zu einem Medium, das sich nicht mehr durch hören abnutzt. Eine Musik zu lieben hinterlässt keine Spuren mehr. Man muss die Musik nicht mehr der Nadel opfern, um sie hören zu können. Vielleicht ist das gerade der Vorteil der CD. Vielleicht passt das Medium CD zu einer Musik, die auch im Hirn keine Spur mehr hinterlaesst.

Wie sagt Agent K noch so treffend: "Dann muss ich mir das weisse Album noch mal kaufen". Am Ende kauft man bei jedem neuen Medium doch nur die alte Musik, weil einem das neue unerträglich erscheint. Und erstmals glaube ich, das nicht am Alter liegt, sondern an der Musik an sich: Wir sind die erste Generation von vor sich hin alternden Erwachsenen, die auf eine Jugend stösst, deren Musik zielgruppenorientiert zielgenau so konzipiert ist, das die geistige Barriere auch für den unmusikalischsten und geistig herausgeforderten Menschen zwischen Hören und Kaufen minimal ist.

Was die Zukunft bringt ? SACD, HDCD, BluRay-CD ? Nur: Unsinn und Sinnentleertheit bleibt auch mit 192 kHz und 96 Bit noch Unsinn und Leere. Nur sechzehn mal so gross.

Donnerstag Aug 23, 2007


Okay ... our stock ticker symbol SUNW will be retired soon. Our new stock ticker symbol is JAVA. Personally, i don´t like it. I don´t like it at all. We´re SUNW. But okay, Jonathan is perfectly right, when he states, that Java is our most powerful brand. But at the end, it´s just a stock ticker symbol and perhaps it´s good to hammer one little fact into the minds of the stock markets: We were the ones, who invented Java ... not BEA or IBM or the like. So at the end, this may be a move, that many technical people doesn´t like. But hey, stock symbols are unimportant for technical people anyway, they were introduced for the beancounting fraction, for the budget planing fraction. And thus, whenever such a person thinks about Java, the person will think at first about the company, which stocksymbol is JAVA. Whenever, someone writes something about us, they will carry "JAVA" forward. And both can only be of positive effect for Sun. At the end it´s all about awareness, at the end it´s all about of closing the circle.

Samstag Aug 18, 2007

House music M.D.

I know someone, who knows someone with access to british television. Thus i was able to get a dvd with three House M.D. episodes. Emergency Room jumped the shark after Season 10, so House is the last only doctors series you can really look. I´m a fan of this series and House is a role model for us ulltracompetent, but antisocial assholes ...
One of the three episodes was House Training (Season 3, Episode 20). At the end (no spoilers here, but you find one here) music starts as usual in modern series. The "bringing the subplots to an end"-music of this episode is excellent. Perfect match to the situation at the end of the episode. With some search in the internet i found the interepret and the title: It´s Follow the leader from the 2006 Mattew Ryan Album "From a late night high rise". An excellent piece of atmospheric music. Give it a try ...



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