4a74580112
For now, this contains the documentation for configuring block devices in configuration files. This file can then be used a common reference for other getting started guides - iscsi, vhost and nvmf targets. Signed-off-by: Jim Harris <james.r.harris@intel.com> Change-Id: Ie6f6c0b3f36dd3fdf418b904462c81a1696b9694
90 lines
3.4 KiB
Markdown
90 lines
3.4 KiB
Markdown
# SPDK bdev Getting Started Guide {#bdev_getting_started}
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Block storage in SPDK applications is provided by the SPDK bdev layer. SPDK bdev consists of:
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* a driver module API for implementing bdev drivers
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* an application API for enumerating and claiming SPDK block devices and performance operations
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(read, write, unmap, etc.) on those devices
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* bdev drivers for NVMe, malloc (ramdisk), Linux AIO and Ceph RBD
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* configuration via SPDK configuration files or JSON RPC
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# Configuring block devices {#bdev_config}
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SPDK block devices are typically configured via an SPDK configuration file. These block devices
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can then be associated with higher level abstractions such as iSCSI target nodes, NVMe-oF namespaces
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or vhost-scsi controllers. This section will describe how to configure block devices for the
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SPDK bdev drivers included with SPDK.
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## NVMe
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The SPDK nvme bdev driver provides SPDK block layer access to NVMe SSDs via the SPDK userspace
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NVMe driver. The nvme bdev driver binds only to devices explicitly specified. These devices
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can be either locally attached SSDs or remote NVMe subsystems via NVMe-oF.
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~~~
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[Nvme]
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# NVMe Device Whitelist
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# Users may specify which NVMe devices to claim by their transport id.
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# See spdk_nvme_transport_id_parse() in spdk/nvme.h for the correct format.
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# The devices will be assigned names in the format <YourName>nY, where YourName is the
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# name specified at the end of the TransportId line and Y is the namespace id, which starts at 1.
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TransportID "trtype:PCIe traddr:0000:00:00.0" Nvme0
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TransportID "trtype:RDMA subnqn:nqn.2016-06.io.spdk:cnode1 traddr:192.168.100.1 trsvcid:4420" Nvme1
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~~~
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This exports block devices for all namespaces attached to the two controllers. Block devices
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for namespaces attached to the first controller will be in the format Nvme0nY, where Y is
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the namespace ID. Most NVMe SSDs have a single namespace with ID=1. Block devices attached to
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the second controller will be in the format Nvme1nY.
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## Malloc
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The SPDK malloc bdev driver allocates a buffer of memory in userspace as the target for block I/O
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operations. This effectively serves as a userspace ramdisk target.
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Configuration file syntax:
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~~~
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[Malloc]
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NumberOfLuns 4
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LunSizeInMB 64
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~~~
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This exports 4 malloc block devices, named Malloc0 through Malloc3. Each malloc block device will
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be 64MB in size.
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## Linux AIO
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The SPDK aio bdev driver provides SPDK block layer access to Linux kernel block devices via Linux AIO.
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Note that O_DIRECT is used and thus bypasses the Linux page cache. This mode is probably as close to
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a typical kernel based target as a user space target can get without using a user-space driver.
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Configuration file syntax:
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~~~
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[AIO]
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# normal file or block device
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AIO /dev/sdb
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AIO /dev/sdc
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~~~
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This exports 2 aio block devices, named AIO0 and AIO1.
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## Ceph RBD
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The SPDK rbd bdev driver provides SPDK block layer access to Ceph RADOS block devices (RBD). Ceph
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RBD devices are accessed via librbd and librados libraries to access the RADOS block device
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exported by Ceph.
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Configuration file syntax:
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~~~
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[Ceph]
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# The format of provided rbd info should be: Ceph rbd_pool_name rbd_name size.
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# In the following example, rbd is the name of rbd_pool; foo is the name of
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# rbd device exported by Ceph; value 512 represents the configured block size
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# for this rbd, the block size should be a multiple of 512.
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Ceph rbd foo 512
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~~~
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This exports 1 rbd block device, named Ceph0.
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