Silent, Durable Media For Servers?

Aldurn asks: "Recently, I've come into a living situation where having my rather loud computer continuously running is distinctly suboptimal. In order to maintain my current email address and webserver, in addition to running a decent set of iptables rules for the house, I decided to buy a Mini-ITX-based server. Currently, /dev/hda is running on a CompactFlash card, but I realize that this probably isn't the best thing to do when running a mail server, due to limitations of the media with regards to the number of writes possible over the lifetime of the media. I'm looking to add another storage medium to the device for /var in order to maintain the logs, as well as for mail storage and other bits that like to live in that directory. The media doesn't have to be terribly large (preferably at least 64 MB), and can be connected through IDE, USB, the floppy connector, or through the network. The end goal of this exercise is simply to prevent my poor CF card from dying an early death from continuous writes. What do you suggest for such a situation?"

Comments

As usual, more than one way to skin this cat.

[Myself]

Seagate has some amazingly quiet drives based on fluid bearings, I'm assuming that this fairly obvious choice has already occured to you and was deemed unsuitable for some reason.

Barring a regular hard drive, the first and most obvious method is a solid-state disk that's designed for continuous use. They're not cheap, but they're totally silent and quite fast, too.

As was already suggested, a RAM disk that periodically backs itself up to CF would work too. RAM is cheap! If you don't need all that CPU power, consider underclocking your setup to reduce the memory's heat generation, and therefore your fan's duty cycle.

You could try a magneto-optical disk. Some of the old 230MB 3.5" MO drives are nearly silent, and the media's rated for millions of writes and decades in storage. I don't know how noisy the 5.25" versions are, but they should be pretty quiet too, mostly owing to low spin speeds and finely machined parts. Again they'd be better as backing stores for a large RAM disk, due to limited i/o speeds and seek times. Being removable, backups are a piece of cake too.

Laptop hard drives are also pretty quiet, because their spindle RPMs are lower than desktop drives (5400 as opposed to 7200 or 10,000). Their platters are also smaller, meaning that the airspeed of the edge of the platter is much lower, creating less turbulence. Being physically smaller also means that you can mount it in rubber vibration isolators, preventing the computer's case from acting as a sounding board for spindle noise and seek clatter.

Also, check hard drive makers' websites for quiet seek modes. The drive's firmware can choose to drive the head servo in a noisy "performance" mode, or to smooth out the edges of the seek motions in a "quiet" mode. It results in a modest performance drop but a distinct reduction in noise.

Next step: Throw the entire computer into an acoustic printer enclosure. Back when impact dot matrix printers were the norm (and they still are in businesses that use multipart forms), everyone hated the racket they made. Elaborate printer cages were built, lined with acoustic foam and equipped with quiet fans to keep the occupant cool. This will drop a few decibels off any obnoxious machine, and they're designed to be easily opened for paper feeding, ribbon changing, etc. The only downside is bulk.

You can also throw bits of acoustoabsorbent foam into the computer's case wherever you find room. I live a few miles from a foam supplier so I picked up a few scraps. Rubber cement or spray-on adhesive work well. Any car stereo shop can sell you little bits of Dynamat, with a self-adhesive backing. An ITX case won't afford much space, but every little bit helps to cut down on panel vibrations and reflected noise.

Good luck!

Don't bother

[swillden]

The end goal of this exercise is simply to prevent my poor CF card from dying an early death from continuous writes.

Don't bother with different media, just use a proper flash file system and don't worry about it. JFFS and JFFS2 are specifically designed for flash file systems, and are purely log-structured, meaning they never erase and rewrite a specific sector, preferring always to write somewhere else in order to level the wear.

To get a rough idea of what the lifetime of you CF card will be, you need to look at how much total data "churn" the card will suffer. Supposing it receives, stores and deletes 10MB of data per day, given a 64 MB CF card, the card will be completely rewritten about every 6.4 days assuming the filesystem job does a perfect job of leveling. It won't, of course, though it will be pretty good. Just to be pessimistic, let's assume that it actually does much worse, and rewrites some part of the chip once per day. That will still give you 273 years of service from your CF card, assuming 100,000 erase cycles (which is the manufacturer's *minimum* guaranteed lifetime -- you'll often see an order of magnitude more cycles before real failures occur).

If you're really paranoid about your e-mail and get a lot of it, replace the card every two years or so (which will likely be after a tiny fraction of a percentage point of the useful lifetime). A 256MB card costs less than $50 right now, and two years from now it'll cost less than dirt.