Re: [PATCH 09/14] target/configfs: Expose protection deviceattributes

From: James Bottomley
Date: Mon Jan 13 2014 - 15:24:17 EST


On Mon, 2014-01-13 at 15:19 -0500, Martin K. Petersen wrote:
> >>>>> "nab" == Nicholas A Bellinger <nab@xxxxxxxxxxxxxxx> writes:
>
> >> What proposed 16 byte scheme? The only DIF proposals I know for
> >> SBC-4 are 13-185R0 and 12-369R0 and that's a couple of new algorithms
> >> and types because we cannot change the 8 byte PI.
>
> nab> Then I'm probably getting the SBC version wrong.. It's the one
> nab> that includes using CRC32C for the block guard, and larger space
> nab> for reference tag as mentioned by MKP.
>
> This is the Type 4 we have been shopping among various vendors. It
> predates and is simpler than HP's proposal (which met resistance in T10
> and was subsequently dropped). So we revived our original Type 4
> proposal which is 16 bytes of protection information per interval
> (CRC32C, 48-bit LBA and 6 bytes of app tag). The proposal has been
> sitting around for a while waiting for SBC-4 to open.

I'm intrigued by this: how do you get the extra space, since I heard all
the drive vendors were adamant that 520 was it for the current
manufacturing processes.

James


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