[ale] [semi OT] encouraging and discouraging HDD and SSD observations

[Ron Frazier (ALE)]

Phil Turmel <philip at turmel.org> wrote:

>On 11/01/2013 08:18 AM, Michael B. Trausch wrote:
>
>> I have 2 TB of data on my regular workstation; however, on any given
>day
>> I don't access even 10% of it, and in any given week I probably been
>> work on one to three projects that are relatively "small" (relative
>to
>> the size of a 100GB SSD, that is).
>> 
>> Thanks for the pointer, there, and I'm totally going to look into
>that.
>
>I was considering it myself recently.  But then I had an unusual task
>where my slow laptop hard drive cost me almost a full day at work.  I'm
>the sole owner of my business, so that made me *angry*, and I
>immediately overnighted a 1T SSD for my laptop. :-).
>
>I'm still interested in bcache, but the urgency kinda' fizzled after
>that.  I suspect that it'll *just work* with the right version of mdadm
>in the initramfs and a suitable mdadm.conf.
>
>Phil


In both my laptops, I have Seagate Hybrid Drives.  Each one has a 4GB or 8GB SSD cache layered on top of a spinning drive.

I think it's a great idea.  They boot almost as fast as an SSD, but have large data capacities of 500 GB and 750 GB respectively but only cost about 30 % over an HDD.  I think the 750 GB one was about $ 130 a year ago.

I would really like all my hard drives to have this capability, but it doesn't seem to have caught on for desktop 7200 and 10000 rpm drives.

As far as I know, the data is still stored on the spinning disk regardless of whether it's in the cache.  That way, if the flash goes south, the data is still there.

If and when I get an SSD, I am definitely planning to get one that has wear level monitoring in the SMART system to monitor the total number of TB written to the drive and show when it's nearing the end of its design life.  I was astounded to find during recent research that, when the memory cells are at the end of life, they may only retain data for 30 days without power.  So, whatever you do, don't leave your old ssd unpowered for any period of time.

And, personally, cost notwithstanding, I would never recommend using an SSD as a backup device.  Data on magnetic drives can last over a decade if the drive is used infrequently and the mechanism continues to work.

Sincerely,

Ron



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Ron Frazier
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