Re: [Nbd] [PATCH 1/3] nbd: support FLUSH requests
- To: Paolo Bonzini <pbonzini@...696...>
- Cc: Andrew Morton <akpm@...133...>, nbd-general@...72..., Paul Clements <Paul.Clements@...124...>, linux-kernel@...25...
- Subject: Re: [Nbd] [PATCH 1/3] nbd: support FLUSH requests
- From: Alex Bligh <alex@...872...>
- Date: Wed, 13 Feb 2013 00:00:13 +0000
- Message-id: <7412A1BC-0383-4539-BCCB-D14FB4206E1B@...872...>
- In-reply-to: <511A8491.5030407@...696...>
- References: <1360685171-3792-1-git-send-email-pbonzini@...696...> <1360685171-3792-2-git-send-email-pbonzini@...696...> <115932E2-48BE-406E-9E75-61D12EB5937A@...872...> <511A8491.5030407@...696...>
Paolo,
On 12 Feb 2013, at 18:06, Paolo Bonzini wrote:
> Il 12/02/2013 18:37, Alex Bligh ha scritto:
>> For my education, why remove the FUA stuff?
>
> Because I had no way to test it.
I think my mods to the official NBD code support FUA (albeit not very efficiently)
>>>>>> Hmmm... the underlying storage could be md/dm RAIDs in which case FUA
>>>>>> should be cheaper than FLUSH.
>>>>
>>>> If someone ever wrote a virtio-blk backend that sits directly ontop
>>>> of the Linux block layer that would be true.
>> In this case we don't know what the backend is sitting on top of
>> a-priori. It might be the current nbd server code, but it might
>> not be.
>
> Do you know of any other NBD server than the "official" one and qemu-nbd?
Yes. I know one well (but it's not open source). NBD seems to be the 'goto protocol' for writing distributed block store drivers in user space.
--
Alex Bligh
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