Messages in this thread | | | Date | Tue, 11 Oct 2011 12:41:34 +0200 | From | Hannes Reinecke <> | Subject | Re: [Patch] SCSI: Retrieve Cache Mode Using SG_ATA_16 if normal routine fails |
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On 10/11/2011 10:26 AM, Amit Sahrawat wrote: > SCSI: Retrieve Cache Mode Using SG_ATA_16 if normal routine fails > > It has been observed that a number of USB HDD's do not respond correctly > to SCSI mode sense command(retrieve caching pages) which results in their > Write Cache being discarded by queue requests i.e., WCE if left set to > '0'(disabled). So, in order to identify the devices correctly - give it > a last try using SG_ATA_16 after failure from normal routine. > I'd be _VERY_ cautious when trying something like this.
ATA_16 is a rather recent command, and most older drives simply can't cope with this. Instead they just kick the error handler and go offline eventually.
Shouldn't we rather use a sensible default, ie assume WCE is enabled?
Cheers,
Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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