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I've recently asked an as-yet-unanswered related question.

My question here is a bit different: I want to know the best way to add storage to a laptop-based system without sacrificing power efficiency or "material efficiency". By the last, I mean anything which would cause the storage elements to deteriorate more rapidly than necessary. The main example I can think of is if spindown happens too infrequently, or perhaps also too frequently, the lifespan of the drive in question may be reduced.

aside

Currently I'm trying to figure out how to get an HP Simplesave 2.5" drive to behave reasonably well. Obviously this is not the optimal choice; it was a boxing week sale which may end up being taken back.

Various tests on it using hdparm seem to indicate that it's not using the value of the -S parameter, which is supposed to determine how long it waits to spin down. Instead, it seems to spin down after 10 seconds if the -B option is set to 127 or less, and after a long period of time, or perhaps not at all, if it is higher. I mention this mainly because I'm not entirely convinced that these directives will tend to work as man hdparm says they should even on drives mounted in proper USB enclosures. The manual does mention that newer enclosures tend to support these features.

main point

The system tends to function mostly as a server, though does see occasional use as a media box. It may get suspended from time to time, or may end up being powered on and active (though idle) for months.

I'd like to have available the same sort of power management functionality that I would get with an internally-mounted HDD in a desktop (or rack-mounted?) server. This includes spinning down and/or sleeping the drive when the server is suspended.

So I'd like to know the best approach to finding an efficient storage solution. Are certain brands of enclosures better for this? Is it necessary to use a 3.5" enclosure, or at least one that is powered separately from the USB line, to get proper power management facilities? Or would I have use a full NAS system for that?

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1 Answer 1

USB drives have a chipset that converts USB mass-storage-device commands to IDE or SATA commands, which the drive then receives. Cheap chipsets (which are the majority, I imagine) don't pass on commands correctly to the drive that aren't directly related to reading or writing data from the drive. You are kind of at the mercy of that hardware with USB enclosures.

Sounds like only the most significant bit of the that -S value is being read by the drive or controller (off (>128) = power save mode, on (<127) = high performance mode)

You might get better feature support if your system has an eSATA port. eSATA talks directly to the drive so there is no "translation" or bridging of commands needed.

In my opinion, the best thing you can do to ensure a long life for a hard drive is:

  • clean power to the system, get a power-conditioning UPS
  • keep the device in a room with a steady ~70 degree temperature and low-humidity
  • minimize powering them on and off, but do power them down if not being used for an extended period of time
  • backups, backups, backups.

I'd say put your money into a UPS and another drive for backup. Do a RAID thing if you like.

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