Re: [Nbd] maximum size of a read/write request
- To: Folkert van Heusden <folkert@...421...>, nbd-general@lists.sourceforge.net
- Subject: Re: [Nbd] maximum size of a read/write request
- From: Alex Bligh <alex@...872...>
- Date: Thu, 06 Oct 2011 22:57:50 +0100
- Message-id: <87FA7F69159E8ECD2EEB533F@...874...>
- Reply-to: Alex Bligh <alex@...872...>
- In-reply-to: <CAFDOyVA=n4uBO9NyGeb6SP5fGc-zSkx81KBuMHskYW8qqf5R3Q@...18...>
- References: <CAFDOyVA=n4uBO9NyGeb6SP5fGc-zSkx81KBuMHskYW8qqf5R3Q@...18...>
--On 6 October 2011 12:53:55 +0200 Folkert van Heusden
<folkert@...421...> wrote:
What is the maximum size of a read/write request? E.g. how much data can
be requested/transmitted using one read or write command?
I do not think there is a protocol limitation.
According to Paul, there is a kernel limitation on how much it will
in practice use, but I am not sure what that is nor whether it
in practice applies if something unconventional (e.g. a hypervisor)
is talking direct to the block layer.
nbd-server is written to handle arbitrary length requests (ok, I
have not checked operations longer than 2^31 bytes).
And can this be limited using a nbd-client command-line setting and/or
nbd protocol handshake?
Not currently.
--
Alex Bligh
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