What: /sys/class/nvme/nvmeX/model What: /sys/class/nvme/nvmeX/serial What: /sys/class/nvme/nvmeX/firmware_rev Date: January 2016 KernelVersion: 4.5 Contact: Keith Busch Description: Shows the model, serial number, or firmware revision string of the NVMe controller, as reported in the Identify Controller data structure. What: /sys/class/nvme/nvmeX/cntlid Date: February 2016 KernelVersion: 4.6 Contact: Ming Lin Description: Shows the controller identifier assigned by the NVMe subsystem. What: /sys/class/nvme/nvmeX/cntrltype What: /sys/class/nvme/nvmeX/dctype Date: February 2022 KernelVersion: 5.18 Contact: Martin Belanger Description: cntrltype: Shows the controller type. Possible values: "io", "discovery", "admin", "reserved". dctype: Shows the discovery controller type. Possible values: "none", "ddc", "cdc", "reserved". What: /sys/class/nvme/nvmeX/reset_controller Date: November 2015 KernelVersion: 4.5 Contact: Christoph Hellwig Description: Write-only. Writing any value triggers a synchronous controller reset. What: /sys/class/nvme/nvmeX/rescan_controller Date: April 2016 KernelVersion: 4.7 Contact: Keith Busch Description: Write-only. Writing any value triggers a namespace rescan on this controller. What: /sys/class/nvme/nvmeX/transport What: /sys/class/nvme/nvmeX/subsysnqn What: /sys/class/nvme/nvmeX/address What: /sys/class/nvme/nvmeX/delete_controller What: /sys/class/nvme/nvmeX/reconnect_delay What: /sys/class/nvme/nvmeX/ctrl_loss_tmo Date: June 2016 KernelVersion: 4.8 Contact: Ming Lin Description: Fabrics controller attributes added with NVMe-oF support. transport: Shows the transport type string. Possible values: "pcie", "tcp", "rdma", "fc", "loop". subsysnqn: Shows the NVMe Qualified Name (NQN) of the subsystem this controller belongs to. address: Shows the transport-specific address string. Only available for fabrics controllers. delete_controller: Write-only. Triggers deletion of this fabrics controller. reconnect_delay: Shows or sets the reconnect delay in seconds. Reading returns the delay value, or "off" if disabled. ctrl_loss_tmo: Shows or sets the controller loss timeout in seconds. Reading returns the timeout value, or "off" if infinite reconnects are allowed. Writing a negative value disables the timeout. What: /sys/class/nvme/nvmeX/hostnqn What: /sys/class/nvme/nvmeX/hostid Date: February 2020 KernelVersion: 5.7 Contact: Sagi Grimberg Description: hostnqn: Shows the host NQN used by this fabrics controller. hostid: Shows the host identifier (UUID format) used by this fabrics controller. Only available for fabrics controllers. What: /sys/class/nvme/nvmeX/fast_io_fail_tmo Date: November 2020 KernelVersion: 5.11 Contact: Victor Gladkov Description: Shows or sets the fast I/O fail timeout in seconds. Reading returns the timeout value, or "off" if disabled. Writing a negative value disables the fast I/O fail. Only available for fabrics controllers. What: /sys/class/nvme/nvmeX/kato Date: April 2021 KernelVersion: 5.13 Contact: Hannes Reinecke Description: Shows the Keep Alive Timeout value in milliseconds for this controller. What: /sys/class/nvme/nvmeX/cmb Date: October 2016 KernelVersion: 4.9 Contact: Stephen Bates Description: Shows the Controller Memory Buffer (CMB) register values in format "cmbloc : 0x%08x\ncmbsz : 0x%08x\n". Only visible when the controller has a CMB (cmbsz != 0). PCI transport only. What: /sys/class/nvme/nvmeX/cmbloc What: /sys/class/nvme/nvmeX/cmbsz What: /sys/class/nvme/nvmeX/hmb Date: July 2021 KernelVersion: 5.15 Contact: Keith Busch Description: cmbloc: Shows the CMBLOC register value. cmbsz: Shows the CMBSZ register value. cmbloc and cmbsz are only visible when the controller has a CMB. PCI transport only. hmb: Shows or sets whether the Host Memory Buffer (HMB) is enabled. Reading returns 1 (enabled) or 0 (disabled). Writing 1 enables HMB; writing 0 disables it. Only visible when the controller supports HMB (hmpre != 0). PCI transport only. What: /sys/class/nvme/nvmeX/state Date: November 2016 KernelVersion: 4.11 Contact: Sagi Grimberg Description: Shows the current state of the controller. Possible values: "new", "live", "resetting", "connecting", "deleting", "deleting (no IO)", "dead". What: /sys/class/nvme/nvmeX/numa_node Date: November 2018 KernelVersion: 5.0 Contact: Hannes Reinecke Description: Shows the NUMA node the controller is attached to. What: /sys/class/nvme/nvmeX/queue_count What: /sys/class/nvme/nvmeX/sqsize Date: September 2019 KernelVersion: 5.4 Contact: James Smart Description: queue_count: Shows the total number of queues (admin + I/O) for this controller. sqsize: Shows the submission queue size for this controller. What: /sys/class/nvme/nvmeX/dhchap_secret What: /sys/class/nvme/nvmeX/dhchap_ctrl_secret Date: June 2022 KernelVersion: 6.0 Contact: Hannes Reinecke Description: dhchap_secret: Shows or sets the host DH-HMAC-CHAP secret for this controller. Reading returns "none" if not set. Writing must use the "DHHC-1:" key format and triggers re-authentication. dhchap_ctrl_secret: Shows or sets the controller DH-HMAC-CHAP secret for bidirectional authentication. Same format as dhchap_secret. Only available when CONFIG_NVME_HOST_AUTH is enabled and for fabrics controllers. What: /sys/class/nvme/nvmeX/tls_key Date: August 2023 KernelVersion: 6.7 Contact: Hannes Reinecke Description: Shows the serial of the currently active TLS PSK as hex. Returns empty if no TLS key is active. Only available for TCP controllers with TLS or secure concatenation enabled (CONFIG_NVME_TCP_TLS). What: /sys/class/nvme/nvmeX/tls_configured_key Date: July 2024 KernelVersion: 6.12 Contact: Hannes Reinecke Description: Shows the serial of the configured TLS key. Writing 0 triggers a PSK reauthentication (REPLACETLSPSK) with the target. After reauthentication the returned serial will be the new key. Only available for TCP controllers with secure concatenation enabled (CONFIG_NVME_TCP_TLS). What: /sys/class/nvme/nvmeX/tls_keyring Date: July 2024 KernelVersion: 6.12 Contact: Hannes Reinecke Description: Shows the TLS keyring description. Only available for TCP controllers with a keyring configured (CONFIG_NVME_TCP_TLS). What: /sys/class/nvme/nvmeX/tls_mode Date: April 2026 KernelVersion: 7.1 Contact: Daniel Wagner Description: Shows the TLS mode: "tls" for direct TLS or "concat" for secure concatenation. Only available for TCP controllers with TLS or secure concatenation enabled (CONFIG_NVME_TCP_TLS). What: /sys/class/nvme/nvmeX/passthru_err_log_enabled Date: January 2024 KernelVersion: 6.8 Contact: Alan Adamson Description: Shows or sets whether admin passthrough error logging is enabled for this controller. Reading returns "on" or "off". Writing accepts a boolean value. What: /sys/class/nvme/nvmeX/quirks Date: November 2025 KernelVersion: 7.0 Contact: Maurizio Lombardi Description: Shows the active quirk names for this controller, one per line. Shows "none" if no quirks are active. What: /sys/class/nvme/nvmeX/admin_timeout What: /sys/class/nvme/nvmeX/io_timeout Date: May 2026 KernelVersion: 7.2 Contact: Maurizio Lombardi Description: admin_timeout: Shows or sets the admin command timeout in milliseconds. io_timeout: Shows or sets the I/O command timeout in milliseconds. Changes are propagated to all namespace request queues. The value must be nonzero. Only writable after the controller has been started at least once. What: /sys/block/nvmeXnY/uuid What: /sys/block/nvmeXnY/eui What: /sys/block/nvmeXnY/nsid Date: December 2015 KernelVersion: 4.5 Contact: Keith Busch Description: Namespace identification attributes. uuid: Shows the UUID for this namespace. Falls back to showing the NGUID for backward compatibility. Hidden if both are all zeros. eui: Shows the IEEE Extended Unique Identifier (EUI-64). Hidden if all zeros. nsid: Shows the namespace identifier (NSID). What: /sys/block/nvmeXnY/wwid Date: February 2016 KernelVersion: 4.6 Contact: Keith Busch Description: Shows the World Wide Identifier for this namespace. The format depends on available identifiers (in priority order): "uuid.{UUID}", "eui.{NGUID}", "eui.{EUI64}", or "nvme.{VID}-{SERIAL}-{MODEL}-{NSID}". What: /sys/block/nvmeXnY/nguid Date: June 2017 KernelVersion: 4.13 Contact: Johannes Thumshirn Description: Shows the Namespace Globally Unique Identifier (NGUID). Hidden if the NGUID is all zeros. What: /sys/block/nvmeXcYnZ/ana_grpid What: /sys/block/nvmeXcYnZ/ana_state Date: May 2018 KernelVersion: 4.19 Contact: Christoph Hellwig Description: ana_grpid: Shows the ANA Group ID for this namespace path device. ana_state: Shows the ANA state. Possible values: "optimized", "non-optimized", "inaccessible", "persistent-loss", "change". Only visible when the controller supports ANA. Requires CONFIG_NVME_MULTIPATH. What: /sys/block/nvmeXcYnZ/queue_depth Date: June 2024 KernelVersion: 6.11 Contact: Thomas Song Description: Shows the current active I/O count on this path's controller. Returns empty if iopolicy is not "queue-depth". Requires CONFIG_NVME_MULTIPATH. What: /sys/block/nvmeXcYnZ/numa_nodes Date: January 2025 KernelVersion: 6.15 Contact: Nilay Shroff Description: Shows the NUMA node mask for which this path is the currently selected path. Returns empty if iopolicy is not "numa". Requires CONFIG_NVME_MULTIPATH. What: /sys/block/nvmeXnY/delayed_removal_secs Date: May 2025 KernelVersion: 6.16 Contact: Nilay Shroff Description: Shows or sets the delayed removal timeout in seconds for the multipath head device. When nonzero, I/O is queued instead of failed when all paths are gone, and head removal is deferred. Only visible on multipath head devices. Requires CONFIG_NVME_MULTIPATH. What: /sys/block/nvmeXnY/csi What: /sys/block/nvmeXnY/metadata_bytes What: /sys/block/nvmeXnY/nuse Date: December 2023 KernelVersion: 6.8 Contact: Daniel Wagner Description: csi: Shows the Command Set Identifier for this namespace. metadata_bytes: Shows the metadata size in bytes. nuse: Shows the Namespace Utilization (NUSE) value. Reading triggers an Identify Namespace command to refresh the value (rate-limited to avoid excessive commands). What: /sys/block/nvmeXnY/passthru_err_log_enabled Date: January 2024 KernelVersion: 6.8 Contact: Alan Adamson Description: Shows or sets whether I/O passthrough error logging is enabled for this namespace. Reading returns "on" or "off". Writing accepts a boolean value. What: /sys/class/nvme/nvmeX/diag/command_error_count What: /sys/class/nvme/nvmeX/diag/reset_count What: /sys/class/nvme/nvmeX/diag/reconnect_count Date: May 2026 KernelVersion: 7.2 Contact: Nilay Shroff Description: Controller diagnostic counters. command_error_count: Admin command error counter. reset_count: Controller reset counter. reconnect_count: Accumulated reconnect counter. Only available for fabrics controllers. All counters can be reset by writing a value. What: /sys/block/nvmeXnY/diag/command_retries_count What: /sys/block/nvmeXnY/diag/command_error_count Date: May 2026 KernelVersion: 7.2 Contact: Nilay Shroff Description: Namespace diagnostic counters for non-multipath configurations (when CONFIG_NVME_MULTIPATH is not configured). command_retries_count: I/O command retry counter. command_error_count: I/O command error counter. All counters can be reset by writing any value. What: /sys/block/nvmeXcYnZ/diag/command_retries_count What: /sys/block/nvmeXcYnZ/diag/command_error_count What: /sys/block/nvmeXcYnZ/diag/multipath_failover_count What: /sys/block/nvmeXnY/diag/io_requeue_no_usable_path_count What: /sys/block/nvmeXnY/diag/io_fail_no_available_path_count Date: May 2026 KernelVersion: 7.2 Contact: Nilay Shroff Description: Namespace diagnostic counters for multipath configurations (when CONFIG_NVME_MULTIPATH is configured). command_retries_count: I/O command retry counter. command_error_count: I/O command error counter. multipath_failover_count: Multipath failover counter. io_requeue_no_usable_path_count: Counter of I/Os requeued because no usable path was available. io_fail_no_available_path_count: Counter of I/Os failed because no available path existed. All counters can be reset by writing any value. What: /sys/class/nvme-subsystem/nvme-subsysX/model What: /sys/class/nvme-subsystem/nvme-subsysX/serial What: /sys/class/nvme-subsystem/nvme-subsysX/firmware_rev What: /sys/class/nvme-subsystem/nvme-subsysX/subsysnqn Date: November 2017 KernelVersion: 4.15 Contact: Hannes Reinecke Description: Shows the model, serial number, firmware revision, or NQN of the NVMe subsystem. What: /sys/class/nvme-subsystem/nvme-subsysX/iopolicy Date: February 2019 KernelVersion: 5.1 Contact: Hannes Reinecke Description: Shows or sets the multipath I/O path selection policy for this subsystem. Accepted values: "numa", "round-robin", "queue-depth". Changing the policy clears all current path selections. Only available when CONFIG_NVME_MULTIPATH is enabled. What: /sys/class/nvme-subsystem/nvme-subsysX/subsystype Date: September 2021 KernelVersion: 5.16 Contact: Hannes Reinecke Description: Shows the subsystem type. Possible values: "discovery", "nvm", "reserved".