Configure flash drives in High I/O instances as Data drives


The two 1.6 TB PCIe flash cards included with the OnMetal I/O flavor come unformatted. Use the following steps to configure your flash cards for use as a data disk.

  1. Set the Linux I/O scheduler to noop.

    echo noop > /sys/block/sdb/queue/scheduler
    echo noop > /sys/block/sdc/queue/scheduler
    
  2. Set the Linux queue configurations for SSD, as follows:

    echo 4096 > /sys/block/sdb/queue/nr_requests
    echo 1024 > /sys/block/sdb/queue/max_sectors_kb
    echo 1 > /sys/block/sdb/queue/nomerges
    echo 512 > /sys/block/sdb/device/queue_depth
    
    echo 4096 > /sys/block/sdc/queue/nr_requests
    echo 1024 > /sys/block/sdc/queue/max_sectors_kb
    echo 1 > /sys/block/sdc/queue/nomerges
    echo 512 > /sys/block/sdc/device/queue_depth
    
  3. Use Linux Software RAID-0 across cards, as follows:

    mdadm --create --verbose /dev/md0 --level=stripe --raid-devices=2 /dev/sdb /dev/sdc
    mkfs.ext4 /dev/md0
    
  4. Add /data mount point entry to fstab:

    mkdir /data
    echo "UUID=`blkid -s UUID -o value /dev/md0`  /data ext4  noatime 0  0" >> /etc/fstab 
    mount /data
    


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