RAID0 mdadm Question

[artur.paszkiewicz@intel.com (Artur Paszkiewicz)]

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