Re: possible usb3-connected hard drive spin down causing lag

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.

-- 
Gary Jennejohn