zfs: copies=n is not a substitute for device redundancy!
Published by Jim Salter // May 2nd, 2016
I’ve been seeing a lot of misinformation flying around the web lately about the zfs dataset-level feature copies=n. To be clear, dangerous misinformation. So dangerous, I’m going to go ahead and give you the punchline in the title of this post and in its first paragraph: copies=n does not give you device fault tolerance! Why does copies=n actually exist then? Well, it’s a sort of (extremely) poor cousin that helps give you a better chance […]
Read MoreEmoji on Ubuntu Trusty
Published by Jim Salter // November 2nd, 2015
OK, so this is maybe kinda useless. But I wanted an emoji ONCE for a presentation, and the ONCE I wanted it, the fool thing wouldn’t display on my presentation laptop and I had to scramble at the last minute to do something that wasn’t quite as entertaining. So here’s how you fix that problem: you@box:~$ sudo apt-get update ; sudo apt-get install ttf-ancient-fonts unifont Poof, you got emojis. In my case, the one I […]
Read MoreGood article benchmarking KVM storage
Published by Jim Salter // October 12th, 2015
http://www.ilsistemista.net/index.php/virtualization/47-zfs-btrfs-xfs-ext4-and-lvm-with-kvm-a-storage-performance-comparison.html Good stuff. Nice in-depth run of several different benchmarks for everything from fileserver to mailserver to database type usage. A bit thin on the ground for configuration, and probably no surprises here if you already read my KVM storage article from 2013, but it’s always nice to get completely independent confirmation. The author’s hardware setup was surprisingly wimpy – an AMD Phenom II with only 8GB of RAM – which may explain part of […]
Read MoreReshuffling ZFS pool storage on the fly
Published by Jim Salter // August 16th, 2015
If you’re new here: Sanoid is an open-source storage management project, built on top of the OpenZFS filesystem and Linux KVM hypervisor, with the aim of providing affordable, open source, enterprise-class hyperconverged infrastructure. Most of what we’re talking about today boils down to “managing ZFS storage” – although Sanoid’s replication management tool Syncoid does make the operation a lot less complicated. Recently, I deployed two Sanoid appliances to a new customer in Raleigh, NC. When […]
Read MoreZFS compression: yes, you want this
Published by Jim Salter // February 24th, 2015
So ZFS dedup is a complete lose. What about compression? Compression is a hands-down win. LZ4 compression should be on by default for nearly anything you ever set up under ZFS. I typically have LZ4 on even for datasets that will house database binaries… yes, really. Let’s look at two quick test runs, on a Xeon E3 server with 32GB ECC RAM and a pair of Samsung 850 EVO 1TB disks set up as a […]
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