On 01/25/2017 04:38 PM, James Bottomley wrote:
On Wed, 2017-01-25 at 15:38 +0100, Hannes Reinecke wrote:
On 01/25/2017 03:27 PM, Ewan D. Milne wrote:
On Wed, 2017-01-25 at 11:38 +0100, Hannes Reinecke wrote:
On 01/25/2017 11:23 AM, Christoph Hellwig wrote:
On Wed, Jan 25, 2017 at 08:26:05AM +0100, Hannes Reinecke
wrote:
For any device with an older SCSI revision we might not
be scanning VPD pages, which results in a wrongly configured
discard mode if thin provisioned is enabled.
According to sbc3 any thin provisioned device (ie devices
which have the LBPME bit set in the output of READ
CAPACITY(16)) need to support VPD pages. So this patch always
enables VPD pages even for older SCSI revisions if thin
provisioning is enabled.
Can you explain what you need this for? A device with a per
-SBC3 revision that wants us to use UNMAP?
Some storage arrays essentially lie about the SCSI revision (most
notably Hitachi :-), and some claim to support SPC-2 (or even
SPC) but support newer features, too. Most notably VPD pages
support. In this case it was an HP EVA claiming to support SPC-2
only, but providing thin provisioning.
Um, isn't this why we added:
commit c1d40a527e885a40bb9ea6c46a1b1145d42b66a0
Author: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Date: Tue Jul 15 12:49:17 2014 -0400
scsi: add a blacklist flag which enables VPD page inquiries
(well, it was for storvsc, but we could add an entry for the HP
EVA)
I knew someone would raise this objection :-)
Thing is, setting 'WS16' here is arguably wrong, as LPBME just means
'logical block provisioning management enabled', not 'WRITE SAME 16
with UNMAP' supported.
And we've set the restriction for scanning VPD pages rather high by
moving it to at least SPC-3; meaning we lose out on all SPC-2 devices
with logical block provisioning.
So rather than blacklisting each and every device (and incurring
loads of customer calls) I'd rather fix it once and for all.
Anything with a capacity over 2TB gets into RC16 .,. that includes a
lot of USB storage nowadays. What would this proposed addition do to
them?
Nothing.
We're latching off the 'LPBME' bit from the READ CAPACITY 16
information, which (hopefully) isn't set.
And the 'skip_vpd_pages' as being set by the USB drives is evaluated at
a later point, so they won't be affected.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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