Pulling apart Ceph’s CRUSH algorithm

By | Technical | One Comment

As you’ve probably noticed, we’ve been evaluating Ceph in recent months for our petabyte-scale distributed storage needs. It’s a pretty great solution and works well, but it’s not the easiest thing to setup and administer properly. One of the bits we’ve been grappling with recently is Ceph’s CRUSH map. In certain circumstances, which aren’t entirely […]

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Bughunting in Ceph’s radosgw: ETags

By | Technical | No Comments

RADOS Gateway (henceforth referred to as radosgw) is an add-on component for Ceph, large-scale clustered storage now mainlined in the Linux kernel. radosgw provides an S3-compatible interface for object storage, which we’re evaluating for a future product offering. We’ve spent the last few days digging through radosgw source trying to nail a some pesky bugs. […]

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Resonance Cachecade

By | Technical | One Comment

We don’t normally post about hardware wankery, but this little piece of shininess appeared for free in some of the newer Dell servers we’ve been ordering, and it actually sounds like it’s not an awful hack. Cachecade is an LSI technology (Dell PERC cards are rebranded gear) that adds a read-cache tier to the RAID […]

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