Re: [SPDK] SPDK nvmeof target/initiator

[Walker, Benjamin <benjamin.walker at intel.com>]

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On Wed, 2017-05-03 at 02:38 +0000, Ramaraj Pandian wrote:
> I don’t think so but want to ask that Can connected target devices be treated
> as local nvme for spdk to work as initiator? Is there any near term plan to
> support SPDK host initiator?
>  

SPDK already contains an NVMe-oF initiator and it happens to be the same library
as the NVMe driver. You can connect to a remote device by simply specifying a
different transport id to spdk_nvme_probe. Since later in this email chain you
talk about RocksDB, I'll use that as an example.

The SPDK backend for RocksDB uses a configuration file that by default is at
/usr/local/etc/spdk/rocksdb.conf. If you followed along with the instructions to
set it up for a local device, at the end of the file you'll see a section like
this:

[Nvme]
  TransportID "trtype:PCIe traddr:0000:02:00.0" Nvme0

That's saying to use the PCI device at the given address as the backing storage.
If you instead want to connect to a remote device using NVMe-oF, simply change
the configuration file to this (ignore word wrap from my email client):

[Nvme]
  TransportID "trtype:RDMA traddr:<ip address> trsvcid:<port> adrfam:IPv4
subnqn:<nqn of target>" Nvme0

For this to work, you'll need to have compiled SPDK with RDMA support. You can
do that by adding CONFIG_RDMA=y to the command line when you type make.

Full disclosure: I've never tested the RocksDB code using a remote device. It
should work, but I've never tried it.

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