Re: [SPDK] lvol_store restored even if base raid not created for single-base raid

[-- Attachment #1: Type: text/plain, Size: 1577 bytes --]


Hello 
I think this is due to the fact that raid bdev in spdk currently do not have persistent metadata. There is a trello ticket for that though. Since there are no raid md, lvol just store it's md in the very first sectors (32kb, not sure) of raid which is in your case maps directly to the first sectors of lower level device, so it could read it even if there is no raid below.  

> What I want is the
> lvol_store will not restored untill base bdev (raid_bdev, in this
> example) is constructed. Is it possible?

I don't think it is possible without raid persistent md. Basically because  examine callback  happens automatically when spdk goes through bdev initialization. And in examine callback of lvol it always read md from device (an find it there).

Best regards 
Aleksei Marov

>Вторник,  6 ноября 2018, 10:17 +03:00 от wuzhouhui <wuzhouhui14(a)mails.ucas.ac.cn>:
>
>Hi,
>Assume that:
>    1. construct raid_bdev on a single nvme_bdev
>    2. construct lvol_store on the raid_bdev
>    3. restart spdk app
>After spdk app started and nvme_bdev constructed, the lvol_store will
>restored even if raid_bdev not constructed. In other words, the
>single-base raid_bdev just like a passthru_bdev. What I want is the
>lvol_store will not restored untill base bdev (raid_bdev, in this
>example) is constructed. Is it possible?
>
>Thanks.
>_______________________________________________
>SPDK mailing list
>SPDK(a)lists.01.org
>https://lists.01.org/mailman/listinfo/spdk


-- 
Маров Алексей