[wellylug] USB 3.0 via PCI-e, & SATA HDD enclosures/docks

[robert pearce]

>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 18 Jul 2011 19:58:09 +1200
> From: Daniel Reurich <daniel at centurion.net.nz>
> Subject: Re: [wellylug] USB 3.0 via PCI-e, & SATA HDD enclosures/docks
> To: Wellington Linux Users Group <wellylug at lists.wellylug.org.nz>
> Message-ID: <4E23E791.8070403 at centurion.net.nz>
> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>
> On 16/07/11 16:33, Cliff Pratt wrote:
> > On 15/07/11 23:41, Ewen McNeill wrote:
> >> On 2011-07-15 20:48 , Cliff Pratt wrote:
> >>> I've removed many (dead) still spinning disks and I've noticed the
> >>> weird gyro effect of tilting a fast spinning disk....
> >>
> >> My general approach for hotswap disk trays is to pull the disk out
> >> enough that it's no longer connected, and then leave it a bit (eg, 30
> >> seconds) for the platters to spin down before doing anything else
> >> with it. I guess (for David's situation) that deliberately telling
> >> the disk to spin down first might save some time there. But such
> >> software commands feel very 1980s "park the heads" like to me...
> >>
> > I agree, in the sense that it was useful at one time, but outlived its
> > usefulness by several years.
> >
> I can't believe this approach is being entertained.  It sounds like a
> recipe for disaster and may result in early failure of the drives.
>
> Hotplug is a feature that allows for the adding and removal of devices
> at an electrical level without causing damage to the componentry and
> logic circuits and sends the OS events on the attaching/removal of
> devices.  It does nothing for protecting the storage medium from failure
> due to badly timed removal or protecting the information being
> stored/retrieved, especially given the amount of cache that spinning
> rust drives have these days.
>
> I don't think it's wise to assume that a drive will just cope with
> having it's comms and power pulled without preparing it for removal
> first, including giving it opportunity to spin down platters and park
> heads.  Given the ever increasing data densities and corresponding
> reduction in acceptable operating tolerances, one can only assume that
> physically moving a drive in whilst the platters are spinning and the
> heads still hovering over the data area is only going to add to wear and
> tear if not cause some more serious damage.



> <snip>


> --
> Daniel Reurich
> Centurion Computer Technology (2005) Ltd
> Ph: 021 797 722
>
>
 I can understand that there is a natural tendency towards caution in all
things involving spinning metal, but imho hot-swapping a sata(2) drive
should not cause unforeseen problems, in particular in regards to shortening
the lifespan. I've hot-swapped drives like this and I've personally seen
no noticeable increase in failure rates, you will of course get corruption
of any files being written at time of power loss, but if the drive isn't
writing at the time its normally ok to pull it, assuming the hardware and
motherboard are in compliance with the standards.

Bear in mind that any moderately modern drive will autopark the heads into a
landing zone of the platter on powerloss using the rotational inertia of the
drive.
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