Spin down HDD after disk sync or before power off

[Warren Block]

On Fri, 29 Jan 2010, Jung-uk Kim wrote:
> On Friday 29 January 2010 05:38 pm, Warren Block wrote:
>
> I am not 100% sure but I think it should be something like the
> attached patch.

Yes, I had the two commands backwards.  So let me try to summarize:

ad_shutdown uses ATA_FLUSHCACHE writes out any cached data, but does not 
park the heads.  At powerdown, the heads do an emergency park, which is 
louder than a normal park and possibly damaging.

Adding ATA_STANDBY_IMMEDIATE after the ATA_FLUSHCACHE will park the 
heads more quietly and possibly more safely.  Should do no harm, at 
least.

ad_spindown looks like it's meant to spin the disk down for sleep 
operations, and does some higher-level things.

I suspect flushcache and standby should be as close together as possible 
to avoid the chance of anything getting back into the cache or spinning 
the disk back up.

Anyway, testing this use of ad_spindown inside ad_shutdown brought back 
the GLINK on shutdown.

A fixed version of the earlier patch that does flushcache and then
standbyimmediate is attached.

-Warren Block * Rapid City, South Dakota USA
-------------- next part --------------
--- sys/dev/ata/ata-disk.c.orig	2010-01-29 18:15:49.000000000 -0700
+++ sys/dev/ata/ata-disk.c	2010-01-29 18:16:47.000000000 -0700
@@ -193,7 +193,10 @@
 
     if (atadev->param.support.command2 & ATA_SUPPORT_FLUSHCACHE)
 	ata_controlcmd(dev, ATA_FLUSHCACHE, 0, 0, 0);
-    return 0;
+
+    if (atadev->param.support.command2 & ATA_SUPPORT_POWERMGT)
+	ata_controlcmd(dev, ATA_STANDBY_IMMEDIATE, 0, 0, 0);
+    return 0;    
 }
 
 static int