Suppose, not hypothetically, that you're replacing a pair of olddisks with a pair of new disks in a ZFS pool that uses mirrors. Ifyou're a cautious person and you worry about issues like infantmortality in your new drives, you don't necessarily want to immediatelyswitch from the old disks to the new ones; you want to run them inparallel for at least a bit of time. ZFS makes this very easy, sinceit supports up to four way mirrors and you can just

Over on Twitter, I said something I've said before :

Once again, here I am hating how Linux introduced additional kernelsecurity modules without also adding an errno for 'the loadablesecurity module denied permissions'.

Lack of a LSM errno significantly complicates debugging problems,especially if you don't normally use LSMs.

Naturally there's a sysadmin story here, but let's start with thebackground (even if you probably know it).

SELinux and Ubuntu's AppArmor are examples of Linux Security Modules

When I added some NVMe drives to my office machine and started looking into its PCIe setup,I discovered that its Radeon graphics card seemed to be operatingat 2.5 GT/s (PCIe 1.0) instead of 8 GT/s (PCIe 3.0). The last timearound, I thought I had fixed this just by poking into the BIOS , but in a comment, Alex suggested that thiswas actually a power-saving measure and not necessarily done bythe BIOS. I'll

One of the unusual things about Wandering Thoughts andall of my web stuff is that it's almost completely unstyled . In particular, I don't try to specify HTML fonts or HTMLfont sizes; I leave it entirely up to your browser, on the assumptionthat your browser knows more about good typography on your systemthan I do. However, this doesn't mean that my entries live in apure world of semantic content, because in practice you can'tdivorce content from its presentation ; how

We've been looking into using ClamAV as part of our anti-spam and anti-malware filtering here , either in addition to ourcurrent commercial filter or as a replacementfor it. While we've been operating ClamAV, we've been looking atand into the things it matches signatures for, and discoveringthings like third party ClamAV signatures include a lot ofphish and spam .

(Depending on the form of the email, some or a lot of the phishand spam is also recognized as 'malware

One of the unusual things that DWiki (the software behind here) doesis that it rejects HTTP GET requests with unknown query parametersand logs them. Usually what this reports is yet another thing usingyet another query parameter for analytics tracking, like Facebookand their ' fbclid=... ' parameter ( cf ), which is a goodpart of why I no longer recommend being cautious in your webapp . But every so often something elseturns up, something that looks a lot like people probing forvulnerable web

For a long time, the way to make Python programs runnable on Unixhas been to start them with ' #!/usr/bin/python ' or sometimes' #!/usr/bin/env python ' (and then chmod them executable, ofcourse; this makes them scripts ).Unfortunately this is no longer a good idea for general Pythonprograms, for the simple reason that current Unixes now disagreeon what version of Python is '/usr/bin/python'. Instead, we all

One of the perennial problems with machines that have multipledrives is figuring out which of your physical drives is sda , whichis sdb , and so on; the mirror problem is arranging things so thatthe drive you want to be the boot drive actually is the first drive.In sanely made server hardware this is generally relatively easy,but with desktops you can run into all sorts of problems, such as how desktop motherboards can wire things up oddly . Under some situations, NVMe drivesmake this easier than with SATA drives

Getting some NVMe drives for my office machine has been an ongoing education into many areas of PCIe, including how to see your PCIe topology with lspci and understanding how PCIe bus addresses and topology relate to eachother . Today I coincidentally discoveredthat there is another way to look into your system's PCIe topology,because it turns out that the Linux kernel materializes it a directoryhierarchy in the sysfs filesystem that is usually mounted on /sys .

Generally, the root of the PCI(e) bus hierarchy is going to