Accelerating a RAID-5 array with a solid-state hard drive.

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A couple of weeks ago, one of my co-workers mentioned in passing that he'd surprised himself by adding an SSD (solid state drive) to his file server at home.  To recap a bit, Leandra, my primary server at home has a sizable RAID-5 array storing all of my data.  However, one of the tradeoffs is that stuff recently written to the array is a little slow to be read back.  It's really not noticeable unless you're logged in and running commands, and even then the lag is something like one or two seconds.  Noticeable but not actually problematic.  At any …

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Life and times.

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Long time readers are probably wondering where I've been lately.  The answer is kind of long and is worth a post all on its own.  The short version of the story is, work's been eating me alive lately.  This is our busiest time of year and it's been all hands on deck for a couple of weeks now.  In point of fact, last week was our quarterly all-hands meeting, where everybody on my team was flown into town for a solid week of meetings.  All day, every day.  Most of my visible activity lately took the form of parts of …

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Gargantuan file servers and tiny operating systems.

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We seem to have reached a unique point in history: Available to your average home user are gargantuan amounts of disk space (8 terabyte hard drives are a thing, and the prices are rapidly coming down to widespread affordability) and enough processing power is available for the palm of your hand that makes the computational power that put the human race on the moon compare in the same was that a grain of sand does to a beach.  For most people, it's the latest phone upgrade or more space for your media box.  For others, though, it poses an unusual …

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Arch Linux, systemd, and RAID.

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Long, long time readers of my blog might remember Leandra, the server that I've had running in my lab in one configuration or another since high school (10th grade, in point of fact). She's been through many different incarnations and has run pretty much every x86 CPU ever made since the 80386. She's also run most of the major distributions of Linux out there, starting with Slackware and most recently running Arch Linux (all of the packages of Gentoo with none of the spending hours compiling everything under the sun or fighting with USE flags). It's also possible to get …

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Well, that worked.

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A couple of days ago, a few "Hey, are you still alive?" messages hit my inbox, and just now have I had the opportunity to post an update.

I've been busy as hell since 2012 started and it shows no signs of letting up. When you work in IT and you take a vacation for 10 days, whether or not something blew up at work isn't the question. The relevant question is actually, "How many things blew up at work?" and the answer is usually a number that can be comfortably counted on one hand... in hexadecimal. Lots of long …

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Logging into a Falcon RAID shelf.

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Publically posted for future reference by sysadmins everywhere.

Regarding the Falcon RAID shelf, model ESA16G1B-0030 (3U high, sixteen SATA drive bays, hardware RAID, SCSI interface, two crappy serial ports (headphone jacks? really? you folks took this whole binary thing way too literally!), Ethernet jack, flip-out ears on the front with a rudimentary control panel on the left-hand side) from RAID, Inc. I just inherited one of these at work with no documentation, warranty, or support for it whatsoever. Consequently, I've spent most of a week trying to figure out how to set the damned thing up. Also, I haven't been …

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Network update: Leandra back online.

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Maintenance on Leandra is finished. I took her offline around 2100 ESET5EDT on Saturday night to remove a dead DVD-ROM drive, remove a pair of 512GB memory modules that weren't doing anything, and swap out her 250 GB hard drive for a 500 GB drive. The RAID array has had 250 GB added to it; specifically, the logical volume holding everything but the /boot and / partitions has had 250 GB added to it. 15 GB from the free pool was added to /usr (so that more software could potentially be installed) and the rest of the free disk space was …

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Working with software RAID in Linux.

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This post assumes that you've worked enough with Linux to know about the existence of software RAID in the Linux v2.6 kernel series, though not necessarily much about it.

If you're not familiar with it, RAID (Redundant Array of Inexpensive Disks) is a set of techniques that replicate data across multiple hard drives on the assumption that, at some point, a drive is going to fail. If the data can be found in some form on another drive, the data is still available. Otherwise you're out of luck unless you made backups, and if you're really unfortunate, your machine …

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