Messages in this thread | | | Date | Tue, 07 Jan 2014 16:28:45 +0800 | From | Ric Wheeler <> | Subject | Re: status of block-integrity |
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On 12/23/2013 09:35 PM, Martin K. Petersen wrote: >>>>>> "Christoph" == Christoph Hellwig <hch@infradead.org> writes: > Christoph> We have the block integrity code to support DIF/DIX in the > Christoph> the tree for about 5 and a half years, and we still don't > Christoph> have a single consumer of it. > > What do you mean? If you have a DIX-capable HBA (lpfc, qla2xxx, zfcp) > then integrity protection is active from the block layer down. The only > code that's not currently being exercised are the tag interleaving > functions. I was hoping the FS people would use them for back pointers > but nobody seemed to bite. > > > Christoph> Given that we'll have a lot of work to do in this area with > Christoph> block multiqueue I think it's time to either kill it off for > Christoph> good or make sure we can actually use and test it. > > I don't understand why multiqueue would require a lot of work? It's just > an extra scatterlist per request. > > And obviously, if there's anything that needs to be done in this area > I'll be happy to do so... >
One of the major knocks on linux file systems (except for btrfs) that I hear is the lack of full data path checksums. DIF/DIX + xfs or ext4 done right will give us another answer here. I don't think it will be common, it is a request that comes in for very large storage customers most commonly.
We do have devices that support this and are working to get more vendor testing done, so I would hate to see us throw out the code instead of fixing it up for the end users that see value here.
I think that we can get this working & agree with the call to continue this discussion (here and at LSF :))
Ric
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