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Hard Drive Spin Down....Good or Bad??

1638 Views 5 Replies Latest reply: Nov 14, 2012 12:24 PM by The hatter RSS
valbelvalbel Calculating status...
Currently Being Moderated
Nov 13, 2012 1:16 PM

'Two questions, really, but first some background.  I have an earlier Mac Pro running 10.7.3 (as I recall).  I also have a Sonos music system.  All the hard drive bays in the Mac Pro are occupied.  The first has a 2 TB Western Digital RE that has my OS and all my files on it.  Bay's 2 and 3 have two 3TB drives from Hitachi which are mirrored and serve as my internal daily backup which is run and cloned by CCC.  The fourth drive is another RE that has copies of all my music.  I simply copy my two iTunes folders and any other music I want the Sonos system to access to this fourth drive.  My reason for doing this is that I wanted to minimize the run time of my main hard drive as not so long ago, I had two Seagate drives go belly up on me.  All the music on the fourth drive (that serves the Sonos system) comes from my main hard drive which is backed up to the two mirrored internal drives as well as a G-Technolgy mirrored external drive, so I'm not concerned with backing up the drive serving the Sonos system.  So......


Question one is:  Which is better for drives in general, to keep them spinning all the time, or to allow or force them to spin down if they aren't being accessed?


Question two is:  If it is better to spin down a drive, how can I selectively spin down some drives and not others? 


For instance, I'm thinking that it is better to spin drives down, then I'd like to be able to spin down drive #1 with my OS but not the Sonos drive because the Sonos system prefers that the drive not spin down or there are connection errors.


Thanks for all your answers and suggestions!

  • Martin Pace Level 5 Level 5 (5,075 points)
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    Nov 13, 2012 4:59 PM (in response to valbelvalbel)

    When a drive spins down it causes slightly more wear and tear on the bearings during the spin up phase than it would if it was just spinning. What the ideal spin down/spin up ratio to always spinning may vary by manufacturerer and I don't know of any analysis that says if the drive spins down for X hours before spinning back up then you'll cause less wear and tear than just always spinning.


    Drives that spin down require more time to access than drives that are spinning so you may see the spinning beachball at times (such as open/save dialog boxes or when launching programs) if the drive has spun down.


    Drives that spin down use less power.


    For people whose objective is to minimize power usage it is better to spin down the drive. For people who want fast data access it's better to leave them spinning.


    Most modern drives have mean time before failures that are greater than 50,000 hours (i.e. more than 5 years) and some go up to 300,000 hours (about 30 years). However, that's a statistical mean so nothing says it can't fail with <1000 hours of use (I've had both Seagate and Western Digital drives fail in <1 year in the recent past).


    There is no right or definate answer to your question. The bottom line is if you value your data you need a back-up plan that takes into account how critical your data is to you and how critical it is to maintain a minimum down time should a disk fail.

  • Grant Bennet-Alder Level 8 Level 8 (48,180 points)
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    Nov 14, 2012 9:29 AM (in response to valbelvalbel)

    I'd prefer not to let the mirrored backup drives spin continuously.

    Mirroring drives is not in and of itself, a form of backup. It merely extends the time-to-repair to help keep a drive failure from becoming a data disaster. You are still subject to human error and "crazy software".


    You should consider changing that Mirored pair into a rotating A, B backup pair or an A,B,C set (backing up to them alternately).

    Mac Pro (Early 2009), Mac OS X (10.6.8), &amp; Server, PPC, &amp; AppleTalk Printers
  • The hatter Level 9 Level 9 (58,600 points)
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    Nov 14, 2012 12:24 PM (in response to valbelvalbel)

    I would investigate SoftRAID 4, it offers a better mirror, scans during idle in background for weak/bad sectors, better rebuillds.


    I tend to think non-mirror but more clones (daily, weekly, monthly sets, and rotate daily so you never lose more than one period).


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