possible usb3-connected hard drive spin down causing lag

[Gary Jennejohn]

On Thu, 26 Nov 2020 10:44:19 -0700
Warner Losh <imp at bsdimp.com> wrote:

> On Thu, Nov 26, 2020 at 4:16 AM Michael Gmelin <freebsd at grem.de> wrote:
> 
> >
> >
> > On Thu, 26 Nov 2020 10:12:06 +0100
> > Gary Jennejohn <gljennjohn at gmail.com> wrote:
> >  
> > > On Thu, 26 Nov 2020 01:14:02 -0700
> > > Warner Losh <imp at bsdimp.com> wrote:
> > >  
> > > > On Thu, Nov 26, 2020 at 1:07 AM Gary Jennejohn
> > > > <gljennjohn at gmail.com> wrote:  
> > > > > On Thu, 26 Nov 2020 00:10:40 +0000
> > > > > tech-lists <tech-lists at zyxst.net> wrote:
> > > > >  
> > > > > > Hi,
> > > > > >
> > > > > > I have a usb3-connected harddrive. dmesg shows this:
> > > > > > [...]
> > > > > > da0: <ADATA HD710 0> Fixed Direct Access SPC-4 SCSI device
> > > > > > [...]
> > > > > >
> > > > > > running current-r367806-arm64
> > > > > >
> > > > > > I think it might be auto-spinning-down or auto-sleeping. It's
> > > > > > making initial interaction lag of 2-3 seconds.  Is there a
> > > > > > sysctl or something somewhere where I can tell it to never
> > > > > > sleep?  Or is that something I'd need to contact the
> > > > > > manufacturer about?  Or is there an alternative strategy like
> > > > > > tmpfs.  It's not a "green" drive but I guess it might be
> > > > > > "green" in that it's usb3 powered.
> > > > > >
> > > > > > I have vfs.read_max=128 in /etc/sysctl.conf
> > > > > > zdb has ashift=12
> > > > > >
> > > > > > In case it's relevant, the filesystem on the disk is zfs. Once
> > > > > > "woken up", inferaction is quick, as expected.
> > > > > > thanks,
> > > > > >  
> > > > >
> > > > > I'd be interested in an answer to this question myself.  I have
> > > > > several USB-attached UFS2 disks which spin down after a few
> > > > > minutes.
> > > > >
> > > > > But, based on some quick searches, this behavior is either a
> > > > > "feature" of the disk itself - seems common with so-called green
> > > > > disks - or of the controller in the external enclosure or docking
> > > > > station.
> > > > >
> > > > > This behavior makes sense for drives used with laptops, but for
> > > > > desktop computers not so useful.
> > > > >
> > > > > There are some sysctl's relevant to spindown, but they appear to
> > > > > only come into play during suspend or shutdown.  The ones
> > > > > relevant to USB which I found are:
> > > > >
> > > > > kern.cam.ada.spindown_suspend: Spin down upon suspend
> > > > > kern.cam.ada.spindown_shutdown: Spin down upon shutdown
> > > > >
> > > > > There may be commands which a user can send the disk/controller to
> > > > > disable this behavior, but I didn't find any with my simple
> > > > > searches.  
> > > >
> > > > For SAS drives, there's a mode page that controls this behavior.
> > > >
> > > > You might see if the sysutil/ataidle port/package does what you
> > > > want.  
> > >
> > > Thanks, Warner, but that port is not in my HEAD ports tree.  It's
> > > also not in the HEAD pkg repository.  Many the name has changed?
> > >
> > > My disks are all SATA in various USB3 enclosures/docking stations.
> > >  
> >
> > I also used ataidle in the past, but it was removed from the ports tree
> > in 2018 (see MOVED).
> >
> > Since then, I'm using camcontrol to set standby timeout values on my
> > SATA drives, I never tried it on USB devices though.
> >
> > Example:
> >
> > /sbin/camcontrol standby /dev/da2 -v -t 1800  
> 
> 
> Perfect! I've not had to deal with sata disks that did this since the
> ataidle days. I looked in camcontrol before suggesting it, but somehow
> missed this... Glad I posted a bogus answer (sorry about that), since I
> learned something new.
> 

camcontrol unfortuantely doesn't work with my USB3 enclosures.  I
suspect that the USB3-to-SATA bridge controller is doing its own thing
and camcontrol has no effect on its behavior.  Not tragic for me since
I use these disks primarily for backups.  But for someone using a USB
attached disk as a primary file system this behavior will definitely be 
a PITA.

-- 
Gary Jennejohn