Linux System Administration

Simple Disk Benchmarking in Linux Using 'dd'

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A great way to do a real-world disk test on your linux system…

What a Resilver Looks Like in ZFS (and a Bug and/or Feature)

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At home I have an (admittedly small) ZFS array set up to experiment with this neat newish raid technology. I think it has been around long enough that it can be used in production, but I'm still getting used to the little bugs/features, and here is one that I just found. After figuring out that I had 2 out of 3 of my 1TB Seagate Barracuda hard drives fail, I had to give the array up for a loss and test out my backup strategy. Fortunately it worked and there was no data loss. After receiving the replacement drives in from RMA, I rebuilt the ZFS array (using raidz again) and went along my merry way. After 6 months or so, I started getting some funky results from my other drive. Thinking it might have some issue as with the others, I removed the drive and ran Seatools on it (by the way, Seatools doesn't offer a 64-bit Windows version - what year is this?). The drive didn't show any signs of failure, so I decided to wipe it and add it back into the array to see what happens. That, of course, is easier said than done.

Disabling The hald-addon-storage Service On CentOS/RedHat

The hald - Hardware Access Layer Daemon - runs several processes…

Adding Random Quotes to the Bash Login Screen

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According to "official" system administrator rules and guidelines…

Fixing ip_conntrack Bottlenecks: The Tale Of The DNS Server With Many Tiny Connections

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I manage a server which has a sole purpose: serving DNS requests. We use PowerDNS, which has been great. It is a DNS server whose backend is SQL, making administration of large numbers of records very easy. It is also fast, easy to use, open source and did I mention it is free? The server has been humming along for years now. The traffic graphs don't show a lot of data moving through it because it only serves DNS requests (plus MySQL replication) in the form of tiny UDP packets. Read on to follow my story of how I fixed this tricky problem. No kittens were harmed in the writing of this post.

Another Bash One Liner To Delete Old Directories

We received a tip from blog readers Christian and Michael for…

One Line Batch Rename Files Using CSV Input File and awk

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The Bash command environment, which is the namesake of this blog,…