AWS EBS NVMe udev rules

70-ec2-nvme-devices.rules

# Copyright (C) 2006-2016 Amazon.com, Inc. or its affiliates.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License").
# You may not use this file except in compliance with the License.
# A copy of the License is located at
#
#    http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
# OF ANY KIND, either express or implied. See the License for the
# specific language governing permissions and limitations under the
# License.

#nvme-ns-* devices
KERNEL=="nvme[0-9]*n[0-9]*", ENV{DEVTYPE}=="disk", ATTRS{serial}=="?*", ATTRS{model}=="?*", SYMLINK+="disk/by-id/nvme-$attr{model}_$attr{serial}-ns-%n", OPTIONS+="string_escape=replace"

#nvme partitions
KERNEL=="nvme[0-9]*n[0-9]*p[0-9]*", ENV{DEVTYPE}=="partition", ATTRS{serial}=="?*", ATTRS{model}=="?*",  IMPORT{program}="ec2nvme-nsid %k"
KERNEL=="nvme[0-9]*n[0-9]*p[0-9]*", ENV{DEVTYPE}=="partition", ATTRS{serial}=="?*", ATTRS{model}=="?*",  ENV{_NS_ID}=="?*", SYMLINK+="disk/by-id/nvme-$attr{model}_$attr{serial}-ns-$env{_NS_ID}-part%n", OPTIONS+="string_escape=replace"

# ebs nvme devices
KERNEL=="nvme[0-9]*n[0-9]*", ENV{DEVTYPE}=="disk", ATTRS{model}=="Amazon Elastic Block Store", PROGRAM="/sbin/ebsnvme-id -u /dev/%k", SYMLINK+="%c"

ebsnvme-id

#!/usr/bin/env python2.7

# Copyright (C) 2017 Amazon.com, Inc. or its affiliates.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License").
# You may not use this file except in compliance with the License.
# A copy of the License is located at
#
#    http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
# OF ANY KIND, either express or implied. See the License for the
# specific language governing permissions and limitations under the
# License.

"""
Usage:
Read EBS device information and provide information about
the volume.
"""

import argparse
from ctypes import *
from fcntl import ioctl
import sys

NVME_ADMIN_IDENTIFY = 0x06
NVME_IOCTL_ADMIN_CMD = 0xC0484E41
AMZN_NVME_VID = 0x1D0F
AMZN_NVME_EBS_MN = "Amazon Elastic Block Store"

class nvme_admin_command(Structure):
    _pack_ = 1
    _fields_ = [("opcode", c_uint8),      # op code
                ("flags", c_uint8),       # fused operation
                ("cid", c_uint16),        # command id
                ("nsid", c_uint32),       # namespace id
                ("reserved0", c_uint64),
                ("mptr", c_uint64),       # metadata pointer
                ("addr", c_uint64),       # data pointer
                ("mlen", c_uint32),       # metadata length
                ("alen", c_uint32),       # data length
                ("cdw10", c_uint32),
                ("cdw11", c_uint32),
                ("cdw12", c_uint32),
                ("cdw13", c_uint32),
                ("cdw14", c_uint32),
                ("cdw15", c_uint32),
                ("reserved1", c_uint64)]

class nvme_identify_controller_amzn_vs(Structure):
    _pack_ = 1
    _fields_ = [("bdev", c_char * 32),  # block device name
                ("reserved0", c_char * (1024 - 32))]

class nvme_identify_controller_psd(Structure):
    _pack_ = 1
    _fields_ = [("mp", c_uint16),       # maximum power
                ("reserved0", c_uint16),
                ("enlat", c_uint32),     # entry latency
                ("exlat", c_uint32),     # exit latency
                ("rrt", c_uint8),       # relative read throughput
                ("rrl", c_uint8),       # relative read latency
                ("rwt", c_uint8),       # relative write throughput
                ("rwl", c_uint8),       # relative write latency
                ("reserved1", c_char * 16)]

class nvme_identify_controller(Structure):
    _pack_ = 1
    _fields_ = [("vid", c_uint16),          # PCI Vendor ID
                ("ssvid", c_uint16),        # PCI Subsystem Vendor ID
                ("sn", c_char * 20),        # Serial Number
                ("mn", c_char * 40),        # Module Number
                ("fr", c_char * 8),         # Firmware Revision
                ("rab", c_uint8),           # Recommend Arbitration Burst
                ("ieee", c_uint8 * 3),      # IEEE OUI Identifier
                ("mic", c_uint8),           # Multi-Interface Capabilities
                ("mdts", c_uint8),          # Maximum Data Transfer Size
                ("reserved0", c_uint8 * (256 - 78)),
                ("oacs", c_uint16),         # Optional Admin Command Support
                ("acl", c_uint8),           # Abort Command Limit
                ("aerl", c_uint8),          # Asynchronous Event Request Limit
                ("frmw", c_uint8),          # Firmware Updates
                ("lpa", c_uint8),           # Log Page Attributes
                ("elpe", c_uint8),          # Error Log Page Entries
                ("npss", c_uint8),          # Number of Power States Support
                ("avscc", c_uint8),         # Admin Vendor Specific Command Configuration
                ("reserved1", c_uint8 * (512 - 265)),
                ("sqes", c_uint8),          # Submission Queue Entry Size
                ("cqes", c_uint8),          # Completion Queue Entry Size
                ("reserved2", c_uint16),
                ("nn", c_uint32),            # Number of Namespaces
                ("oncs", c_uint16),         # Optional NVM Command Support
                ("fuses", c_uint16),        # Fused Operation Support
                ("fna", c_uint8),           # Format NVM Attributes
                ("vwc", c_uint8),           # Volatile Write Cache
                ("awun", c_uint16),         # Atomic Write Unit Normal
                ("awupf", c_uint16),        # Atomic Write Unit Power Fail
                ("nvscc", c_uint8),         # NVM Vendor Specific Command Configuration
                ("reserved3", c_uint8 * (704 - 531)),
                ("reserved4", c_uint8 * (2048 - 704)),
                ("psd", nvme_identify_controller_psd * 32),     # Power State Descriptor
                ("vs", nvme_identify_controller_amzn_vs)]  # Vendor Specific

class ebs_nvme_device:
    def __init__(self, device):
        self.device = device
        self.ctrl_identify()

    def _nvme_ioctl(self, id_response, id_len):
        admin_cmd = nvme_admin_command(opcode = NVME_ADMIN_IDENTIFY,
                                       addr = id_response,
                                       alen = id_len,
                                       cdw10 = 1)

        with open(self.device, "rw") as nvme:
            ioctl(nvme, NVME_IOCTL_ADMIN_CMD, admin_cmd)

    def ctrl_identify(self):
        self.id_ctrl = nvme_identify_controller()
        self._nvme_ioctl(addressof(self.id_ctrl), sizeof(self.id_ctrl))

        if self.id_ctrl.vid != AMZN_NVME_VID or self.id_ctrl.mn.strip() != AMZN_NVME_EBS_MN:
            raise TypeError("[ERROR] Not an EBS device: '{0}'".format(self.device))

    def get_volume_id(self):
        vol = self.id_ctrl.sn

        if vol.startswith("vol") and vol[3] != "-":
            vol = "vol-" + vol[3:]

        return vol

    def get_block_device(self, stripped=False):
        dev = self.id_ctrl.vs.bdev

        if stripped and dev.startswith("/dev/"):
            dev = dev[5:]

        return dev

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Reads EBS information from NVMe devices.")
    parser.add_argument("device", nargs=1, help="Device to query")

    display = parser.add_argument_group("Display Options")
    display.add_argument("-v", "--volume", action="store_true",
            help="Return volume-id")
    display.add_argument("-b", "--block-dev", action="store_true",
            help="Return block device mapping")
    display.add_argument("-u", "--udev", action="store_true",
            help="Output data in format suitable for udev rules")

    if len(sys.argv) < 2:
        parser.print_help()
        sys.exit(1)

    args = parser.parse_args()

    get_all = not (args.udev or args.volume or args.block_dev)

    try:
        dev = ebs_nvme_device(args.device[0])
    except (IOError, TypeError) as err:
        print >> sys.stderr, err
        sys.exit(1)

    if get_all or args.volume:
        print "Volume ID: {0}".format(dev.get_volume_id())
    if get_all or args.block_dev or args.udev:
        print dev.get_block_device(args.udev)

ec2nvme-nsid

#!/bin/bash

# Copyright (C) 2006-2016 Amazon.com, Inc. or its affiliates.
# All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License").
# You may not use this file except in compliance with the License.
# A copy of the License is located at
#
#    http://aws.amazon.com/apache2.0/
#
# or in the "license" file accompanying this file. This file is
# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS
# OF ANY KIND, either express or implied. See the License for the
# specific language governing permissions and limitations under the
# License.

#Expected input if partition's kernel name like nvme0n1p2
if [ $# -eq 0 ] ; then
  exit 1
else
  # extract ns id from partition's kernel name and export it
  NSID=$(echo -n "$@" | cut -f 3 -d 'n' | cut -f 1 -d 'p')
  echo "_NS_ID=${NSID}"
fi

Wouldnt it better to map to UUID disk values? that way if anyone changes the name of the AWS mount via cli or console it will always be the same

creating a symlink might be an issue if the volume is removed and the instance is rebooted.. the link stays and potentially be pointing to the wrong volume...

speaking of disk UUID.. it would be nice if theebsnvme-id script would output it. as an option

could be done with

blkid -s UUID -o value $VOLUME_ID

where $VOLUME_ID is lowercase and "-" stripped

this would also be nice to be able to search with the volume id as well to return the device via the ebsnvme-id script

example seach by volume id

./ebsnvme-id -t volume-id vol0a7b5c0b5901d1741
Volume ID: vol-0a7b5c0b5901d1741
/dev/nvme7n1
`

These were originally pulled from an Amazon Linux AMI image and are unmodified from when they were originally extracted.

That being said, one of the main purposes of these scripts is to provide mappings from nvme device names to the older /dev/sdb//dev/xvdb naming convention that is displayed on the AWS console (or provided via AWS API).

In that case, you would actually want the symlink to update if you change the block name of the device. Also, keep in mind that the block device name is provided by AWS as a vendor specific attribute of the nvme device.