[smartmontools-support] NVMe drive

[James]

I just installed an nvme drive in my old computer.
Why is there 2 devices?
/dev/nvme0
/dev/nvme0n1



$ sudo smartctl -a /dev/nvme0n1
smartctl 6.6 2016-05-31 r4324 [x86_64-linux-4.18.0-14-generic] (local build)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Number:                       HP SSD EX900 250GB
Serial Number:                      HBSE28480300247
Firmware Version:                   R0802B0
PCI Vendor ID:                      0x1dee
PCI Vendor Subsystem ID:            0x126f
IEEE OUI Identifier:                0x000000
Controller ID:                      1
Number of Namespaces:               1
Namespace 1 Size/Capacity:          250,059,350,016 [250 GB]
Namespace 1 Formatted LBA Size:     512
Local Time is:                      Wed Feb  6 17:34:04 2019 EST
Firmware Updates (0x06):            3 Slots
Optional Admin Commands (0x0006):   Format Frmw_DL
Optional NVM Commands (0x005f):     Comp Wr_Unc DS_Mngmt Wr_Zero 
Sav/Sel_Feat *Other*
Maximum Data Transfer Size:         64 Pages
Warning  Comp. Temp. Threshold:     70 Celsius
Critical Comp. Temp. Threshold:     80 Celsius

Supported Power States
St Op     Max   Active     Idle   RL RT WL WT  Ent_Lat  Ex_Lat
  0 +     9.00W       -        -    0  0  0  0        0       0

Supported LBA Sizes (NSID 0x1)
Id Fmt  Data  Metadt  Rel_Perf
  0 +     512       0         0

=== 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:                        54 Celsius
Available Spare:                    100%
Available Spare Threshold:          10%
Percentage Used:                    0%
Data Units Read:                    24 [12.2 MB]
Data Units Written:                 5,223 [2.67 GB]
Host Read Commands:                 504
Host Write Commands:                10,348
Controller Busy Time:               0
Power Cycles:                       5
Power On Hours:                     0
Unsafe Shutdowns:                   4
Media and Data Integrity Errors:    0
Error Information Log Entries:      0
Warning  Comp. Temperature Time:    0
Critical Comp. Temperature Time:    0

Error Information (NVMe Log 0x01, max 256 entries)
Num   ErrCount  SQId   CmdId  Status  PELoc          LBA NSID    VS
  24 18446744073709551615     0  0x0000  0x0000  0x000 0     0     -
  25 18446744073709551615     -       -       -      - -     -  0xff
  45 4607182419872710656     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248     -
  48 4607182419872710656 21520  0x0080  0x5410  0x080 
4607182419872710656 1072693248     -
  49 4607182419872710656     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248     -
  50 4607182419872710656     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248     -
  51 4607182419872710656     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248     -
  52 4607182418800017408     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248  0x10
  53 1072693248     0  0x3ff0  0x0000 0x3ff0 4607182419872710656 
1072693248     -
  55 4607182419872710656     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248     -
  58 4607182419872710656     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248     -
  59 4607182419872710656     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248     -
  60 4607182419872710656     0  0x3ff0  0x0000 0x3ff0 
4607182419872710656 1072693248     -
  61 300662063104  1792  0x2007  0x0100  0x001 585129164603648 131072     -
  64 2251804122611968     0  0x0028  0x0080  0x000 2533291979112704 
14024704  0x80
  65 1125904215638272     0  0x00a5  0x0080  0x000 1407392074105088 
13893632  0x80

... (109 entries not shown)


What are the errors in the NVMe Log?
What is an unsafe shutdown?