Linux – EC2 instance initializing with only 1/2 check thus not able to login into the Linux server

Hello friends,

Our EC2 instance is initializing with only " 1/2 checks passed " after I detached and reattached my volumes (I did it for some specific debugging purpose). Thus i am not able to login into my Linux server now (using putty .. it shows network error) where I have some complex scripts which i need to retrieve in case we decide to terminate the instance.

I don't know much abt EC2 programming as we only use it for SAP HANA cloud access.I have generated a SYSTEM LOG of the instance which shown below:

souvenir Xen Minimal OS!
  start_info: 0x9248000(VA)
    nr_pages: 0x1117000
  shared_inf: 0x7e68b000(MA)
     pt_base: 0x924b000(VA)
nr_pt_frames: 0x4d
    mfn_list: 0x990000(VA)
   mod_start: 0x0(VA)
     mod_len: 0
       flags: 0x0
    cmd_line: root=/dev/sda1 ro 4
  stack:      0x94f860-0x96f860
MM: Init
      _text: 0x0(VA)
     _etext: 0x6000d(VA)
   _erodata: 0x78000(VA)
     _edata: 0x80b00(VA)
stack start: 0x94f860(VA)
       _end: 0x98fe68(VA)
  start_pfn: 929b
    max_pfn: 1117000
Mapping memory range 0x9400000 - 0x1117000000
setting 0x0-0x78000 readonly
skipped 0x1000
MM: Initialise page allocator for 11b4d000(11b4d000)-1117000000(1117000000)
MM: done
Demand map pfns at 1117001000-3117001000.
Heap resides at 3117002000-5117002000.
Initialising timer interface
Initialising console ... done.
gnttab_table mapped at 0x1117001000.
Initialising scheduler
Thread "Idle": pointer: 0x3117002010, stack: 0x1113680000
Initialising xenbus
Thread "xenstore": pointer: 0x31170027c0, stack: 0x1113690000
Dummy main: start_info=0x96f960
Thread "main": pointer: 0x3117002f70, stack: 0x11136a0000
"main" "root=/dev/sda1" "ro" "4" 
vbd 2049 is hd0
******************* BLKFRONT for device/vbd/2049 **********


backend at /local/domain/0/backend/vbd/390/2049
Failed to read /local/domain/0/backend/vbd/390/2049/feature-barrier.
Failed to read /local/domain/0/backend/vbd/390/2049/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2144 is hd1
******************* BLKFRONT for device/vbd/2144 **********


backend at /local/domain/0/backend/vbd/390/2144
Failed to read /local/domain/0/backend/vbd/390/2144/feature-barrier.
Failed to read /local/domain/0/backend/vbd/390/2144/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2160 is hd2
******************* BLKFRONT for device/vbd/2160 **********


backend at /local/domain/0/backend/vbd/390/2160
Failed to read /local/domain/0/backend/vbd/390/2160/feature-barrier.
Failed to read /local/domain/0/backend/vbd/390/2160/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2176 is hd3
******************* BLKFRONT for device/vbd/2176 **********


backend at /local/domain/0/backend/vbd/390/2176
Failed to read /local/domain/0/backend/vbd/390/2176/feature-barrier.
Failed to read /local/domain/0/backend/vbd/390/2176/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2192 is hd4
******************* BLKFRONT for device/vbd/2192 **********


backend at /local/domain/0/backend/vbd/390/2192
Failed to read /local/domain/0/backend/vbd/390/2192/feature-barrier.
Failed to read /local/domain/0/backend/vbd/390/2192/feature-flush-cache.
20971520 sectors of 512 bytes
**************************
vbd 2208 is hd5
******************* BLKFRONT for device/vbd/2208 **********


backend at /local/domain/0/backend/vbd/390/2208
Failed to read /local/domain/0/backend/vbd/390/2208/feature-barrier.
Failed to read /local/domain/0/backend/vbd/390/2208/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2224 is hd6
******************* BLKFRONT for device/vbd/2224 **********


backend at /local/domain/0/backend/vbd/390/2224
Failed to read /local/domain/0/backend/vbd/390/2224/feature-barrier.
Failed to read /local/domain/0/backend/vbd/390/2224/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
[H[J

    GNU GRUB  version 0.97  (71680000K lower / 0K upper memory)



       [ Minimal BASH-like line editing is supported.   For

         the   first   word,  TAB  lists  possible  command

         completions.  Anywhere else TAB lists the possible

         completions of a device/filename. ]




grubdom>                                                                       [9;10HXen Minimal OS!
  start_info: 0x9248000(VA)
    nr_pages: 0x1117000
  shared_inf: 0x7e692000(MA)
     pt_base: 0x924b000(VA)
nr_pt_frames: 0x4d
    mfn_list: 0x990000(VA)
   mod_start: 0x0(VA)
     mod_len: 0
       flags: 0x0
    cmd_line: root=/dev/sda1 ro 4
  stack:      0x94f860-0x96f860
MM: Init
      _text: 0x0(VA)
     _etext: 0x6000d(VA)
   _erodata: 0x78000(VA)
     _edata: 0x80b00(VA)
stack start: 0x94f860(VA)
       _end: 0x98fe68(VA)
  start_pfn: 929b
    max_pfn: 1117000
Mapping memory range 0x9400000 - 0x1117000000
setting 0x0-0x78000 readonly
skipped 0x1000
MM: Initialise page allocator for 11b4d000(11b4d000)-1117000000(1117000000)
MM: done
Demand map pfns at 1117001000-3117001000.
Heap resides at 3117002000-5117002000.
Initialising timer interface
Initialising console ... done.
gnttab_table mapped at 0x1117001000.
Initialising scheduler
Thread "Idle": pointer: 0x3117002010, stack: 0x1113680000
Initialising xenbus
Thread "xenstore": pointer: 0x31170027c0, stack: 0x1113690000
Dummy main: start_info=0x96f960
Thread "main": pointer: 0x3117002f70, stack: 0x11136a0000
"main" "root=/dev/sda1" "ro" "4" 
vbd 2049 is hd0
******************* BLKFRONT for device/vbd/2049 **********


backend at /local/domain/0/backend/vbd/391/2049
Failed to read /local/domain/0/backend/vbd/391/2049/feature-barrier.
Failed to read /local/domain/0/backend/vbd/391/2049/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2144 is hd1
******************* BLKFRONT for device/vbd/2144 **********


backend at /local/domain/0/backend/vbd/391/2144
Failed to read /local/domain/0/backend/vbd/391/2144/feature-barrier.
Failed to read /local/domain/0/backend/vbd/391/2144/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2160 is hd2
******************* BLKFRONT for device/vbd/2160 **********


backend at /local/domain/0/backend/vbd/391/2160
Failed to read /local/domain/0/backend/vbd/391/2160/feature-barrier.
Failed to read /local/domain/0/backend/vbd/391/2160/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2176 is hd3
******************* BLKFRONT for device/vbd/2176 **********


backend at /local/domain/0/backend/vbd/391/2176
Failed to read /local/domain/0/backend/vbd/391/2176/feature-barrier.
Failed to read /local/domain/0/backend/vbd/391/2176/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2192 is hd4
******************* BLKFRONT for device/vbd/2192 **********


backend at /local/domain/0/backend/vbd/391/2192
Failed to read /local/domain/0/backend/vbd/391/2192/feature-barrier.
Failed to read /local/domain/0/backend/vbd/391/2192/feature-flush-cache.
20971520 sectors of 512 bytes
**************************
vbd 2208 is hd5
******************* BLKFRONT for device/vbd/2208 **********


backend at /local/domain/0/backend/vbd/391/2208
Failed to read /local/domain/0/backend/vbd/391/2208/feature-barrier.
Failed to read /local/domain/0/backend/vbd/391/2208/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
vbd 2224 is hd6
******************* BLKFRONT for device/vbd/2224 **********


backend at /local/domain/0/backend/vbd/391/2224
Failed to read /local/domain/0/backend/vbd/391/2224/feature-barrier.
Failed to read /local/domain/0/backend/vbd/391/2224/feature-flush-cache.
41943040 sectors of 512 bytes
**************************
[H[J

    GNU GRUB  version 0.97  (71680000K lower / 0K upper memory)



       [ Minimal BASH-like line editing is supported.   For

         the   first   word,  TAB  lists  possible  command

         completions.  Anywhere else TAB lists the possible

         completions of a device/filename. ]




grubdom>                                                                       [9;10H

Hope u experts can help me with this issue.

thanx

Best Answer

I've had this happen as well -- the second health check is network connectivity, and until that gets sorted out SSH is not going to work (obviously). I would suggest

A full reboot of the instance from within the AWS console or AWS CLI.
You may also want to detach the elastic IP of the instance, wait a few seconds and then re-attach it.

You could also spin up a new EC2 instance in the same AZ, detach the volume from your unhealthy instance, and mount it as a secondary/tertiary volume in the new instance -- either to examine it, or to get out the scripts/files you need.

Sorry I can't give more concrete advice beyond that, but I am wondering if your /local/ partition has become unreadable?

Best Answer

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