From this article, you will learn about NVMe, it’s characteristics, and NVMe-CLI.
Introduction
NVMe (Non-Volatile Memory Express) is a specification for accessing drives via PCI Express; it is specifically tailored to the needs of non-volatile memory. The connection via PCIe Gen3 x4 (32 GBit/s) offers, for example, up to five times faster access speeds and lower latencies than conventional SATA 3 (6GBit/s) interfaces. Thanks to a high degree of parallelism and low energy consumption, they let users meet current and future memory requirements.
Characteristics
NVMe SSDs are addressed differently than SATA drives. In a UNIX system (Linux/BSD), the first NVMe-SSD is called /dev/nvme0n1
instead of /dev/sda
. The n
after nvme0
stands for “Namespace”. The first partition on this SSD is /dev/nvme0n1p1
instead of /dev/sda1
.
The scheme is:
/dev/nvme<CONTROLLER_NUMBER>n<NAMESPACE>p<PARTITION>
NVMe-CLI
To manage NVMe SSDs, you can use the nvme-cli tool on UNIX systems.
Show a list of all detected NVMe SSDs
nvme list
Node SN Model Version Namespace Usage Format FW Rev
---------------- -------------------- ---------------------------------------- -------- --------- -------------------------- ---------------- --------
/dev/nvme0n1 S1XXNYAGAXXXXX SAMSUNG MZVPV512HDGL-00000 1.1 1 102.40 GB / 512.11 GB 512 B + 0 B BXW7300Q
/dev/nvme1n1 S1XXNYAGAYYYYY SAMSUNG MZVPV512HDGL-00000 1.1 1 102.40 GB / 512.11 GB 512 B + 0 B BXW7300Q
Show the serial number of a specific NVMe SSD
nvme id-ctrl /dev/nvme0n1|egrep "sn |mn "
sn : S1XXNYAGAXXXXX
mn : SAMSUNG MZVPV512HDGL-00000
Show the SMART log
SMART stands for Self-Monitoring, Analysis and Reporting Technology. Some NVMe SSD models support the SMART log read out using the tool smartctl
. It is also used for SATA drives and might provide more details for you than if you used the nvme
tool.
Using Smartctl
smartctl -a /dev/nvme0n1
smartctl 6.6 2017-11-05 r4594 [x86_64-linux-4.19.101] (local build)
Copyright (C) 2002-17, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
[...]
=== START OF SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
SMART/Health Information (NVMe Log 0x02, NSID 0x1)
Critical Warning: 0x00
Temperature: 29 Celsius
Available Spare: 100%
Available Spare Threshold: 10%
Percentage Used: 0%
Data Units Read: 113,446 [58.0 GB]
Data Units Written: 48,760 [24.9 GB]
Host Read Commands: 111,504,973
Host Write Commands: 41,507,430
Controller Busy Time: 1,395
Power Cycles: 7
Power On Hours: 395
Unsafe Shutdowns: 0
Media and Data Integrity Errors: 0
Error Information Log Entries: 0
Warning Comp. Temperature Time: 0
Critical Comp. Temperature Time: 0
Temperature Sensor 1: 29 Celsius
Temperature Sensor 2: 30 Celsius
Error Information (NVMe Log 0x01, max 64 entries)
No Errors Logged
Using NVMe-CLI
nvme smart-log /dev/nvme0n1
Smart Log for NVME device:nvme0n1 namespace-id:ffffffff
critical_warning : 0
temperature : 29 C
available_spare : 100%
available_spare_threshold : 10%
percentage_used : 0%
data_units_read : 113,446
data_units_written : 48,760
host_read_commands : 111,504,973
host_write_commands : 41,507,430
controller_busy_time : 1,395
power_cycles : 7
power_on_hours : 395
unsafe_shutdowns : 0
media_errors : 0
num_err_log_entries : 0
Warning Temperature Time : 0
Critical Composite Temperature Time : 0
Temperature Sensor 1 : 29 C
Temperature Sensor 2 : 30 C
Show the error log
nvme error-log /dev/nvme0n1
Error Log Entries for device:nvme0n1 entries:1
.................
Entry[ 0]
.................
error_count : 0
sqid : 0
cmdid : 0
status_field : 0(SUCCESS: The command completed successfully)
parm_err_loc : 0
lba : 0
nsid : 0
vs : 0
cs : 0
.................
Perform a self-test
You can start a short self-test (duration: up to 1h) for checking the NVMe SSDs health using the following command:
nvme device-self-test /dev/nvme0n1 -s 1
Once the self test has been started, you can use this command to check the current state:
nvme self-test-log /dev/nvme0n1
- Output, while the test is running:
Test is 21% complete and is still in progress.
- If the output of the named command states
0%
, the test is either not running, or not supported by the installed NVMe SSD:Test is 0% complete and is still in progress.
- Once the test has been finished, please re-check the SMART health data (see the regarding section in this article).