The state of supporting many groups over NFS v3 in various Unixes
One of the long standing limits with NFSv3 is that the protocolonly uses 16 groups ; although you can bein lots of groups on both the client and the server, the protocolitself only allows the client to tell the server about 16 of them.This is a real problem for places (like us) who have users who wantor need to be in lots of groups for access restriction reasons .
For a long time the only thing you could was shrug and work aroundthis by adding and removing
I should keep and check notes even on my own little problems
I mentioned yesterday that I had a serious issue when I installed a VMWare Workstation update, going from 12.1.0 to 12.1.1.I wound up being very grumpy about it, disrupted the remaining part of mywork day, filed a support request with VMWare, and so on, and eventuallyVMWare support came through with the cause and a workaround ..
It turns out that I could have avoided all of that, because I raninto this same problem back when I upgraded to
A story of the gradual evolution of network speeds without me noticing
A long time ago I had a 28.8Kbps dialupconnection running PPP (it lasted a surprisingly long time ). A couple of times I really needed to run a graphicalX program from work while I was at home, so I did ' ssh -X work 'and then started whatever program it was. And waited. And waited.Starting and using an X program that is moving X protocol trafficover a 28.8K link gives you a lot of time to watch the details of
You should plan for your anti-spam scanner malfunctioning someday
Yesterday I mentioned that the commercialanti-spam and anti-virus system we use ran into a bug where it hungup on some incoming emails. One reaction to this is to point andlaugh; silly us for using a commercial anti-spam system, we probablygot what we deserved here. I think that this attitude is a mistake.
The reality is that all modern anti-spam and anti-virus systems aregoing to have bugs. It's basically inherent in the nature of thebeast. These
You should probably track what types of files your users get in email
Most of the time our commercial anti-spam system works fine and wedon't have to think about it or maintain it (which is one of thegreat attractions of using a commercial system for this). Today wasnot one of those times. This morning, we discovered that someincoming email messages we were receiving make its filtering processeshang using 100% CPU; after a while, this caused all inbound emailto stop. More specifically, the dangerous incoming messages appearedto be a burst of
How 'there are no technical solutions to social problems' is wrong
One of the things that you will hear echoing around the Internetis the saying that there are no technical solutions to socialproblems. This is sometimes called ' Ranum 's Law', where it'sgenerally phrased as 'you can't fix people problems with software'( cf ).Years ago you probably could have found me nodding along sagely tothis and full-heartedly agreeing with it. However, I've changed;these days, I disagree with the spirit of the saying.
It is
Bad slide navigation on the web and understanding why it's bad
As usual, I'll start with my tweet :
If the online copy of your slide presentation is structured in 2D, notjust 'go forward', please know that I just closed my browser window.
This is sort of opaque because of the 140 character limitation, solet me unpack it.
People put slide decks for their presentations online using variousbits of technology. Most of the time how you navigate through thosedecks is strictly linear; you have 'next slide' and 'previous slide
Why you mostly don't want to do in-place Linux version upgrades
I mentioned yesterday that we don't doin-place distribution upgrades, eg to go from Ubuntu 12.04 to 14.04;instead we rebuild starting from scratch. It's my view that in-placeupgrades of at least common Linux distributions are often a badidea for a server fleet even when they're supported. I have threereasons for this, in order of increasing importance.
First, an in place upgrade generally involves more service downtimeor at least instability than
Why we have CentOS machines as well as Ubuntu ones
I'll start with the tweets that I ran across semi-recently (via @bridgetkromhout ):
@alicegoldfuss :If you're running Ubuntu and some guy comes in and says 'we should useRedhat'...fuck that guy." - @mipsytipsy #SREcon16
mipsytipsy :alright, ppl keep turning this into an OS war; it is not. supportingmultiple things is costly so try to avoid it.
This is absolutely true. But, well, sometimes you wind up withexceptions
Why I think Illumos/OmniOS uses PCI subsystem IDs
As I mentioned yesterday , PCI has bothvendor/device IDs and 'subsystem' vendor/device IDs. Here is whatthis looks like (in Linux) for a random device on one of our machineshere (from ' lspci -vnn ', more or less):
04:00.0 Serial Attached SCSI controller [0107]: LSI Logic /Symbios Logic SAS2308 PCI-Express Fusion-MPT SAS-2 [1000:008