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From: "Peter Münster" <pmlists@free.fr>
To: linux-pm@vger.kernel.org
Subject: Re: prevent disk from spinning up at system resume
Date: Mon, 23 Mar 2015 15:36:20 +0100	[thread overview]
Message-ID: <877fu7hjbv.fsf@roche-blanche.net> (raw)
In-Reply-To: Pine.LNX.4.44L0.1503231015390.1336-100000@iolanthe.rowland.org

On Mon, Mar 23 2015, Alan Stern wrote:

> Why does the disk need to be mounted if you aren't using it more than 
> once a week or so?  Why not mount it only while it is in use?

The workflow would be quite different:
normal workflow:
- application needs file on sdb
- sdb spins up
- application can open the file

workflow with unmounted sdb:
- application needs file on sdb
- error message: no such file (or similar)
- user sees error message: "oh dear, the file is on sdb..."
- superuser needs to "add-single-device" and mount it
- user can continue with application


> The kernel wakes up _every_ device during system resume, even ones that
> were in runtime suspend when the system suspend started.  With only a
> few exceptions, there is no way around this in the current kernel.

Even after  "echo 0 >/sys/block/sdb/device/scsi_disk/2:0:0:0/manage_start_stop" ?

If there wasn't the "Synchronizing SCSI cache" at system resume, would
the disk spin up nevertheless?

-- 
           Peter


  reply	other threads:[~2015-03-23 14:36 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-23 11:02 prevent disk from spinning up at system resume Peter Münster
2015-03-23 13:57 ` Alan Stern
2015-03-23 14:07   ` Peter Münster
2015-03-23 14:19     ` Alan Stern
2015-03-23 14:36       ` Peter Münster [this message]
2015-03-23 15:03         ` Alan Stern

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