134 lines
5.1 KiB
Plaintext
134 lines
5.1 KiB
Plaintext
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What: /sys/class/rnbd-client
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Date: Feb 2020
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KernelVersion: 5.7
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Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
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Description: Provide information about RNBD-client.
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All sysfs files that are not read-only provide the usage information on read:
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Example::
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# cat /sys/class/rnbd-client/ctl/map_device
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> Usage: echo "sessname=<name of the rtrs session> path=<[srcaddr,]dstaddr>
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> [path=<[srcaddr,]dstaddr>] device_path=<full path on remote side>
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> [access_mode=<ro|rw|migration>] > map_device
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>
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> addr ::= [ ip:<ipv4> | ip:<ipv6> | gid:<gid> ]
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What: /sys/class/rnbd-client/ctl/map_device
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Date: Feb 2020
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KernelVersion: 5.7
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Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
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Description: Expected format is the following::
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sessname=<name of the rtrs session>
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path=<[srcaddr,]dstaddr> [path=<[srcaddr,]dstaddr> ...]
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device_path=<full path on remote side>
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[access_mode=<ro|rw|migration>]
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Where:
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sessname:
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accepts a string not bigger than 256 chars, which identifies
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a given session on the client and on the server.
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I.e. "clt_hostname-srv_hostname" could be a natural choice.
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path:
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describes a connection between the client and the server by
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specifying destination and, when required, the source address.
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The addresses are to be provided in the following format::
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ip:<IPv6>
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ip:<IPv4>
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gid:<GID>
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for example::
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path=ip:10.0.0.66
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The single addr is treated as the destination.
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The connection will be established to this server from any client IP address.
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::
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path=ip:10.0.0.66,ip:10.0.1.66
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First addr is the source address and the second is the destination.
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If multiple "path=" options are specified multiple connection
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will be established and data will be sent according to
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the selected multipath policy (see RTRS mp_policy sysfs entry description).
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device_path:
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Path to the block device on the server side. Path is specified
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relative to the directory on server side configured in the
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'dev_search_path' module parameter of the rnbd_server.
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The rnbd_server prepends the <device_path> received from client
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with <dev_search_path> and tries to open the
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<dev_search_path>/<device_path> block device. On success,
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a /dev/rnbd<N> device file, a /sys/block/rnbd<N>/
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directory and an entry in /sys/class/rnbd-client/ctl/devices
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will be created.
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If 'dev_search_path' contains '%SESSNAME%', then each session can
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have different devices namespace, e.g. server was configured with
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the following parameter "dev_search_path=/run/rnbd-devs/%SESSNAME%",
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client has this string "sessname=blya device_path=sda", then server
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will try to open: /run/rnbd-devs/blya/sda.
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access_mode:
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the access_mode parameter specifies if the device is to be
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mapped as "ro" read-only or "rw" read-write. The server allows
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a device to be exported in rw mode only once. The "migration"
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access mode has to be specified if a second mapping in read-write
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mode is desired.
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By default "rw" is used.
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nr_poll_queues
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specifies the number of poll-mode queues. If the IO has HIPRI flag,
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the block-layer will send the IO via the poll-mode queue.
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For fast network and device the polling is faster than interrupt-base
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IO handling because it saves time for context switching, switching to
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another process, handling the interrupt and switching back to the
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issuing process.
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Set -1 if you want to set it as the number of CPUs
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By default rnbd client creates only irq-mode queues.
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NOTICE: MUST make a unique session for a device using the poll-mode queues.
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Exit Codes:
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If the device is already mapped it will fail with EEXIST. If the input
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has an invalid format it will return EINVAL. If the device path cannot
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be found on the server, it will fail with ENOENT.
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Finding device file after mapping
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---------------------------------
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After mapping, the device file can be found by:
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o The symlink /sys/class/rnbd-client/ctl/devices/<device_id>@<session_name>
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points to /sys/block/<dev-name>. The last part of the symlink destination
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is the same as the device name. By extracting the last part of the
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path the path to the device /dev/<dev-name> can be build.
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* /dev/block/$(cat /sys/class/rnbd-client/ctl/devices/<device_id>@<session_name>/dev)
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How to find the <device_id> of the device is described on the next
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section.
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What: /sys/class/rnbd-client/ctl/devices/
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Date: Feb 2020
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KernelVersion: 5.7
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Contact: Jack Wang <jinpu.wang@cloud.ionos.com> Danil Kipnis <danil.kipnis@cloud.ionos.com>
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Description: For each device mapped on the client a new symbolic link is created as
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/sys/class/rnbd-client/ctl/devices/<device_id>@<session_name>, which points
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to the block device created by rnbd (/sys/block/rnbd<N>/).
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The <device_id> of each device is created as follows:
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- If the 'device_path' provided during mapping contains slashes ("/"),
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they are replaced by exclamation mark ("!") and used as as the
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<device_id>. Otherwise, the <device_id> will be the same as the
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"device_path" provided.
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