Re: [gentoo-user] External hard drive and idle activity

[Dale]

Bill Kenworthy wrote:
> On 2/1/20 10:27 am, Dale wrote:
>> Mick wrote:
>>> On Thursday, 2 January 2020 00:09:14 GMT Dale wrote:
>>>> Howdy,
>>>>
>>>> As some may recall, I have a 8TB external SATA hard drive that I do
>>>> back
>>>> ups on.  Usually, I back up once a day, more often if needed. 
>>>> Usually I
>>>> turn the power on, mount it, do the back ups, unmount and turn the
>>>> power
>>>> back off.  Usually it is powered up for 5 minutes or so.  When I
>>>> unmount
>>>> it tho, I sometimes notice it is still doing something.  I can feel
>>>> the
>>>> mechanism for the heads moving.  It has a slight vibration to it.
>>>> Questions are, what is it doing and should I let it finish before
>>>> powering it off?  I'd assume that once it in unmounted, the copy
>>>> process
>>>> is done so the files are safe.  I guess it is doing some sort of
>>>> internal checks or something but I'm not sure.
>>> There is some delay with data still in the buffers between
>>> rsync/cp/tar/what-
>>> ever saying it's finished on your terminal and the drive itself
>>> finishing
>>> storing the data on the platters.
>>>
>>> If you look at vmstat, or keep an eye on Gkrelm you'll see what I mean.
>>> Normally, if you try to unmount a drive while it is still being
>>> written to,
>>> the umount/udisks command will complain the drive is busy.
>>>
>> When it does it for a somewhat short period of time, I can understand
>> that.  It's one reason I try to leave it on when it "feels" that it is
>> still busy.  Thing is, there are times when it goes on for 30 minutes or
>> more.  At those times, even a USB stick should be done.  One would think
>> at least.  It makes me curious as to what it is doing in that case.
>> Still, I'd rather the unmount command force a wait until it is done.
>> Honestly, I wouldn't want a drive or software that says something is
>> done when it isn't.  It's not good even when shutting a system down.
>> Given the speed of drives, I would think a few seconds at most.  Best to
>> be safe.  ;-)  I just wonder, is it doing two different things?  One
>> when it is busy for short periods of time and something else when it
>> goes on for a while.  This is what sort of puzzles me.  Selftest maybe??
>>
>>>> Is it safe to turn it off even tho it is doing whatever it is doing?
>>>> Should I wait?  Does it matter?
>>>>
>>>> Thanks.
>>>>
>>>> Dale
>>>>
>>>> :-)  :-)
>>> If you wait for a few seconds after the backup is completed before
>>> you unmount
>>> the drive, you should be OK.  Although it may slow down or any LEDs
>>> flash less
>>> frequently the drive may not stop spinning, unless there is some
>>> power save
>>> process taking control of it.
>>>
>> Given the speed, it is likely done when I tell the KDE thingy to
>> unmount.  Usually, I start the backup and walk away for a few minutes.
>> I do it with one of my scripts, if one can call what I do a script, and
>> it does the date command at the end.  Even if there was a lot of
>> changes, I can tell how long it was completed.  I try to give it a
>> couple minutes.  Still, good point.  This is one reason I'm asking about
>> this.  It's hard to know exactly what is going on here.
>>
>>>> P. S. Down to last router that was discussed in another thread so I
>>>> bought it while they had it.  Price may go up if I didn't.  Did more
>>>> research on old modem, it is risky to try to convert to AT&T.  Some
>>>> say
>>>> not possible.
>>> Right, ISP controlled firmware typically requires re-flashing the
>>> device with
>>> the new ISP's firmware version.  In some cases even the boot code needs
>>> replacing.  Should you flash the router with a wrong firmware build,
>>> you could
>>> sometimes derive a door stop without additional cost.  In this case
>>> you'll
>>> need a JTAG and access to its circuit board with an OEM
>>> boot/firmware version
>>> to recover it.  In most cases OEMs support lines will redirect you
>>> to your
>>> ISP, who run an overseas support line and will ask you to reboot your
>>> MSWindows PC ... O_o
>>>
>>> This is a reason I avoid these kind of routers as much as I can.
>>>
>> Keep in mind, two pieces of hardware.  Router for the first two
>> sentences and Modem for next two.  Tried to be short so . . . . Anyway,
>> router should be flashable with Openwrt.  It's a slightly older model.
>> New model may be ready for flashing in a year or two but not so much at
>> the moment so I went with the older model. The modem, I never could find
>> the firmware.  I found links to it but those links ended up being dead.
>> Even if I had it, it was unlikely to work.  Possible but I'd be
>> concerned about its stability and such even if it did take it. I have a
>> modem and router on the way.  I just didn't want to miss the deal on the
>> router.  They had several a couple weeks or so ago.  I got the last
>> one.  Waiting for their arrival.
>>
>> Dale
>>
>> :-)  :-)
>>
>> Oh, I may post and see if anyone needs a Frontier modem later.  Maybe
>> someone on here could use a spare or just needs one period, moving or
>> something.  Modem is wireless with a router as well.  Nice modem I
>> guess.
>>
>
> Try atop from sys-process/atop - it will show you how busy individual
> disks are (and a lot of other stats as well.)
>
> You can issue a sync command to flush any disk buffers before
> unmounting (umounting should sync as well.).  The heads may keep
> moving because of the internal data management modern disks do. The
> disks should be safe to power off despite this (they have an internal
> flush/save/park routine on power loss, with enough energy stored to
> take care of it)
>
> Bill

Tried atop, it works best for this since it showed the drive device
instead of process name like iotop.  In my case, it shows sdj.  I turned
the drive on, atop showed nothing until I mounted it.  I then did a
quick back up and it showed up like it should.  Once done, it showed no
activity until I told KDE to unmount.  After it was unmounted, it showed
no further activity according to atop, iotop or anything else for that
matter.  I could however feel it doing something.  The heads were moving
around every few seconds or so.  Sometimes close together, sometimes
several seconds or more apart.  It's sort of intermittent type activity.

I might add, the light that shows activity on the enclosure shows
nothing either.  The light is odd, it's always on but blinks when there
is activity.  Usually they are off and come on when active.  Sort of
weird but OK. 

I think once unmounted, the files are done, or a short time afterwards. 
After that, I think you and other are right, it's doing some internal
stuff. 

Thanks again to all who replied.  I'm not 100% sure of what it is doing
but pretty sure I can power it off once the back up is done and it is
unmounted. 

Dale

:-)  :-)