What is the "better / best " method to multi-boot different OSes natively WITHOUT VirtualBox(es) ?

Valeri Galtsev galtsev at kicp.uchicago.edu
Mon Oct 26 21:25:12 UTC 2020

On 10/26/20 3:45 PM, RW via freebsd-questions wrote:
> On Mon, 26 Oct 2020 17:51:04 +0100
> Ralf Mardorf wrote:
>> On Mon, 2020-10-26 at 15:30 +0000, RW via freebsd-questions wrote:
>>> On Sun, 25 Oct 2020 17:33:21 +0100
>>> Polytropon wrote:
>>>> On Sun, 25 Oct 2020 06:50:25 +0100, Ralf Mardorf wrote:
>>>>> I also want to add for consideration, if reboots between
>>>>> operating systems are often wanted and HDDs are used, it's way
>>>>> better when all drives, even the unused drives are spinning all
>>>>> the time. Parking and releasing heads very often, does shorten
>>>>> the life span the most.
>>> I think this is mostly a myth.
>> In my experiences it isn't a myth.
> Note that I was talking specifically about head parking rather then
> power cycling in general. Your anecdote is about power cycling, not
> specifically parking.

Is parking heads not just powering off magnet that positions heads on 
data tracks? My guess is it is, id so, then it has physical mechanism to 
make life finite (I've seen drives that "lost their heads" after too 
many bags of spring loaded against arm stopper).

Constantly spinning drives wears bearings, but bearings are designed to 
last decade if not longer. I have drives that spin for at leas a decade 
and a half almost constantly (with occasional reboots). Worst case 
scenario is poorly balanced platter assembly drive whose axes is 
horizontal. Then bearing wear becomes not uniform, but elliptical 
(gravity adds asymmetry), and at some point of bearing wear platter may 
start vibrate, and that cases fast failure.

But these are speculative reasons based on "mock physics" ;-)


>> The intern HDDs of my PCs did last
>> for around 2 years, when turning the computer off and on several
>> times a day and they did last for around 7 years, if the machine runs
>> more or less 24/7.
> I have contrary anecdotes that I wont bore you with.
>>> A few year ago Western Digital made some green drives, with
>>> extremely aggressive power saving, that parked within seconds. With
>>> some usage patters these could fail in months. I think it was
>>> around this time that people started talking about heads as if they
>>> were like sledge hammers.
>> This is not true.
> And yet you go on to say that it probably is.
>> ... There probably were a few drives where this happened every few
>> seconds,
> Obviously those where it did happen are what I'm talking about. The
> drives were only available for a short period, WD changed the defaults
> back when they started to fail. My recollection is that this
> notion that parking is hugely violent and wearing started to spread
> around that time.
> Some of the explanations about why parking is so bad are absurd. I've
> even heard it said that the whole thing is left to a spring.
> My understanding is that parking is always controlled and performed
> under power, with the spindle motor being used as a generator if
> necessary.
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247

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