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From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Max Gurtovoy <maxg@mellanox.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
	<linux-block@vger.kernel.org>, <axboe@kernel.dk>,
	<linux-nvme@lists.infradead.org>, <keith.busch@intel.com>,
	<hch@lst.de>, <sagi@grimberg.me>, <shlomin@mellanox.com>,
	<israelr@mellanox.com>
Subject: Re: [PATCH v4 1/3] block: centralize PI remapping logic to the block layer
Date: Tue, 10 Sep 2019 21:16:32 -0400	[thread overview]
Message-ID: <yq1k1affx8v.fsf@oracle.com> (raw)
In-Reply-To: <61ab22ba-6f2d-3dbd-3991-693426db1133@mellanox.com> (Max Gurtovoy's message of "Wed, 11 Sep 2019 01:27:29 +0300")


Max,

> I guess Type 1 and Type 3 mirrors can work because Type 3 doesn't have
> a ref tag, right ?

It will work but you'll lose ref tag checking on the Type 3 side of the
mirror. So not exactly desirable. And in our experience, the ref tag is
hugely important.

Also, there are probably some headaches lurking in the slightly
different app/ref tag escape handling if you mix the two
formats. Whereas Type 1 and 2 are 100% identical in behavior if you use
the LBA as the ref tag.

>> Anyway. So my take on all this is that the T10-DIF-TYPE1-CRC profile is
>> "it" and everything else is legacy.
>
> do you see any reason to support the broken type 3 ?

Only to support existing installations. We can't really remove it
without the risk of breaking something for somebody out there.

-- 
Martin K. Petersen	Oracle Linux Engineering

WARNING: multiple messages have this Message-ID (diff)
From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Max Gurtovoy <maxg@mellanox.com>
Cc: axboe@kernel.dk, keith.busch@intel.com, sagi@grimberg.me,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	israelr@mellanox.com, linux-nvme@lists.infradead.org,
	linux-block@vger.kernel.org, shlomin@mellanox.com, hch@lst.de
Subject: Re: [PATCH v4 1/3] block: centralize PI remapping logic to the block layer
Date: Tue, 10 Sep 2019 21:16:32 -0400	[thread overview]
Message-ID: <yq1k1affx8v.fsf@oracle.com> (raw)
In-Reply-To: <61ab22ba-6f2d-3dbd-3991-693426db1133@mellanox.com> (Max Gurtovoy's message of "Wed, 11 Sep 2019 01:27:29 +0300")


Max,

> I guess Type 1 and Type 3 mirrors can work because Type 3 doesn't have
> a ref tag, right ?

It will work but you'll lose ref tag checking on the Type 3 side of the
mirror. So not exactly desirable. And in our experience, the ref tag is
hugely important.

Also, there are probably some headaches lurking in the slightly
different app/ref tag escape handling if you mix the two
formats. Whereas Type 1 and 2 are 100% identical in behavior if you use
the LBA as the ref tag.

>> Anyway. So my take on all this is that the T10-DIF-TYPE1-CRC profile is
>> "it" and everything else is legacy.
>
> do you see any reason to support the broken type 3 ?

Only to support existing installations. We can't really remove it
without the risk of breaking something for somebody out there.

-- 
Martin K. Petersen	Oracle Linux Engineering

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

  reply	other threads:[~2019-09-11  1:17 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-08 15:26 [PATCH v4 1/3] block: centralize PI remapping logic to the block layer Max Gurtovoy
2019-09-08 15:26 ` Max Gurtovoy
2019-09-08 15:26 ` [PATCH v4 2/3] block: don't remap ref tag for T10 PI type 0 Max Gurtovoy
2019-09-08 15:26   ` Max Gurtovoy
2019-09-09  2:22   ` Martin K. Petersen
2019-09-09  2:22     ` Martin K. Petersen
2019-09-09  2:36     ` Keith Busch
2019-09-09  2:36       ` Keith Busch
2019-09-09  2:49       ` Martin K. Petersen
2019-09-09  2:49         ` Martin K. Petersen
2019-09-09 13:31         ` Max Gurtovoy
2019-09-09 13:31           ` Max Gurtovoy
2019-09-08 15:26 ` [PATCH v4 3/3] nvme: remove PI values definition from NVMe subsystem Max Gurtovoy
2019-09-08 15:26   ` Max Gurtovoy
2019-09-09  2:21 ` [PATCH v4 1/3] block: centralize PI remapping logic to the block layer Martin K. Petersen
2019-09-09  2:21   ` Martin K. Petersen
2019-09-09 13:55   ` Max Gurtovoy
2019-09-09 13:55     ` Max Gurtovoy
2019-09-10  2:29     ` Martin K. Petersen
2019-09-10  2:29       ` Martin K. Petersen
2019-09-10 22:27       ` Max Gurtovoy
2019-09-10 22:27         ` Max Gurtovoy
2019-09-11  1:16         ` Martin K. Petersen [this message]
2019-09-11  1:16           ` Martin K. Petersen
2019-09-11  9:12           ` Max Gurtovoy
2019-09-11  9:12             ` Max Gurtovoy
2019-09-13 22:20             ` Martin K. Petersen
2019-09-13 22:20               ` Martin K. Petersen
2019-09-16  8:03               ` Christoph Hellwig
2019-09-16  8:03                 ` Christoph Hellwig
2019-09-16 17:19                 ` Martin K. Petersen
2019-09-16 17:19                   ` Martin K. Petersen

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