RAID0 mdadm Question

[Hiroyuki Sato]

Hello Artur

Thank you for your replying.

I found /dev/md126. But It does not contain partition information.
I'm not sure why partition information lost.

Could you tell me if you know any other commands?

Best regards.


Step1 scan drives

  mdadm --assemble --scan
  mdadm: Container /dev/md/imsm0 has been assembled with 2 drives
  mdadm: Started /dev/md/0_0 with 2 devices


  # cat /proc/mdstat
  Personalities : [raid0]
  md127 : inactive nvme0n1[1](S) nvme1n1[0](S)
        6306 blocks super external:imsm

  md126 : active raid0 nvme1n1[1] nvme0n1[0]
        781416448 blocks super external:/md127/0 128k chunks

  unused devices: <none>

Step2 check partition information

  parted /dev/md126
  GNU Parted 3.1
  Using /dev/md126
  Welcome to GNU Parted! Type 'help' to view a list of commands.
  (parted) p
  Error: /dev/md126: unrecognised disk label
  Model: Linux Software RAID Array (md)
  Disk /dev/md126: 800GB
  Sector size (logical/physical): 512B/512B
  Partition Table: unknown
  Disk Flags:

2016-05-31 22:54 GMT+09:00 Artur Paszkiewicz <artur.paszkiewicz at intel.com>:
> On 05/31/2016 11:41 AM, Hiroyuki Sato wrote:
>> Hello
>>
>> NVMe Newbie question.
>>
>> I have two P3600 PCIe NVMe Cards.
>> And I created RAID0 volume with mdadm command.
>> It works fine. But after reboot, I can't mount file system it.
>> It seems lost partition table.
>> (No partition information)
>>
>> Environment
>>   - NVMe: Intel P3600 cards * 2
>>   - Linux: 4.4.0
>>   - OS: CentOS7
>>
>> Question
>>
>>   1, Do I need re-create file system on each Boot time?
>>
>>   2, If not What step is missing?
>>
>>     generate mdadm.conf?
>>
>> Best regards.
>>
>> NVMe RAID step
>>
>>   Basically I followed this doc
>>     https://communities.intel.com/community/itpeernetwork/blog/2015/10/01/how-to-use-and-benchmark-nvme-ssd-create-a-software-raid-and-analyze-performance-the-answers-are-here
>>
>>   Step1: create container
>>
>>     mdadm -C /dev/md/imsm0 /dev/nvme0n1 /dev/nvme1n1 -n 2 -e imsm -f
>>     mdadm: /dev/nvme0n1 appears to be part of a raid array:
>>            level=raid0 devices=0 ctime=Thu Jan  1 09:00:00 1970
>>     Continue creating array? y
>>     mdadm: container /dev/md/imsm0 prepared.
>>
>>   Step2, create md device
>>     mdadm -C /dev/md0 /dev/md/imsm0 -n 2 -l 0 -c 128 -f
>>     mdadm: array /dev/md0 started.
>>
>>   Step3: Create Partition
>>     parted /dev/md0
>>
>>     (parted) mkpart
>>     Partition name?  []?
>>     File system type?  [ext2]? xfs
>>     Start? 0%
>>     End? -1
>>
>>     (parted) p
>>     Model: Linux Software RAID Array (md)
>>     Disk /dev/md0: 800GB
>>     Sector size (logical/physical): 512B/512B
>>     Partition Table: gpt
>>     Disk Flags:
>>
>>     Number  Start   End    Size   File system  Name  Flags
>>      1      1049kB  800GB  800GB
>>
>>     (parted) quit
>>     Information: You may need to update /etc/fstab.
>>
>>   Step4: Newfs
>>
>>     /sbin/mkfs.xfs -K /dev/md0p1 -f
>>
>>   Step5: mount
>>
>>     mount -o noatime,nodiratime,nobarrier /dev/md0p1 /mnt/nvme1
>>
>
> Maybe the array has not assembled automatically after reboot. Check
> /proc/mdstat.  Also, the device you created in step 2 could have
> assembled under a different name, like /dev/md126.
>
> Artur
>



-- 
Hiroyuki Sato