If this patch is valid , when can we expect this on mainstream kernel . I can help testing this patch when included in the kernel. Narayanan -----Original Message----- From: Matthew Wilcox [mailto:matthew@xxxxxx] Sent: Friday, February 20, 2009 10:35 PM To: James Bottomley Cc: Rengarajan, Narayanan (STSD); linux-scsi@xxxxxxxxxxxxxxx Subject: Re: [PATCH 1/1] : Spinning up disk is observed on standby paths until timeout, resulting in longer path restoration time. On Fri, Feb 20, 2009 at 04:24:08PM +0000, James Bottomley wrote: > I think the point is that it's a transition: Once it comes out of it > we either get access or we don't, so it's worth waiting to see what > happens. I agree. If we knew that it could only be transitioning to inactive, we could skip it. This state probably only gets returned once in a blue moon anyway. > > I don't know what 'Enable Spinup' is for -- maybe Doug knows? > > Sending a START_STOP to the device might be exactly what they intend for us to do. > > Under a 'First, Do No Harm' theory, perhaps we should leave well > > enough alone and just add Standby and Unavailable? > > As I said, it's a SAS power management command related condition: The > drive is limited to consuming a certain level of power and that's not > enough to spin up, so it won't spin up regardless of how many start > unit commands it gets sent until the power management control is > changed to allow it to consume enough power for the spinup. I think > it's ignorable for now ... it probably means that when power > management is added we need to get the transport classes involved to > send the appropriate sas pm command. Looking at SAS2r14, I see that NOTIFY (ENABLE SPINUP) is a primitive, not a command. If the SAS device is attached through an expander, I don't think we have a way to send that primitive to the device. We must wait for the expander to send it. If it's sirectly-connected, the initiator port is supposed to send it. Presumably this is handled either by firmware on the HBA or by the HBA driver; either way, we don't seem to have a way today to get the HBA to send this primitive. I think our current behaviour is correct for this command, so the patch here: http://marc.info/?l=linux-scsi&m=123513805527153&w=2 is correct. -- Matthew Wilcox Intel Open Source Technology Centre "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
