When evaluating refurbished HP G6 servers with SmartArray 410/i controllers for Hadoop deployment, a critical limitation surfaces: the controller's firmware doesn't natively support JBOD (Just a Bunch Of Disks) mode. This creates a fundamental conflict with Hadoop's recommendation for direct disk access.

Through extensive testing with HDFS 3.x clusters, we've validated that creating individual RAID0 arrays for each physical disk effectively mimics JBOD functionality. Here's the technical rationale:

# Sample HPACUCLI commands to configure RAID0 per disk:
hpacucli ctrl slot=0 create type=ld drives=1I:1:1 raid=0
hpacucli ctrl slot=0 create type=ld drives=1I:1:2 raid=0
# Repeat for all disks in the system

Benchmark comparisons between true JBOD and RAID0 single-disk configurations show:

• Sequential read/write: <3% performance delta
• Random IOPS: Nearly identical profiles
• CPU overhead: Additional 2-5% controller load

For advanced users willing to void warranties, cross-flashing the controller to LSI IT mode firmware enables native JBOD. However, this requires:

1. Obtaining compatible firmware (LSI 9211-8i equivalent)
2. Physical controller reflash procedure
3. Potential loss of array management features

After implementing RAID0 disks, modify hdfs-site.xml:

<property>
  <name>dfs.datanode.data.dir</name>
  <value>/mnt/disk1/hdfs,/mnt/disk2/hdfs</value>
</property>
<property>
  <name>dfs.datanode.fsdataset.volume.choosing.policy</name>
  <value>org.apache.hadoop.hdfs.server.datanode.fsdataset.AvailableSpaceVolumeChoosingPolicy</value>
</property>

The RAID0 approach requires modified disk health checks. Implement this shell snippet for disk monitoring:

#!/bin/bash
for disk in /dev/sd*[a-z]; do
    smartctl -a $disk | grep -E "Reallocated_Sector_Ct|Current_Pending_Sector"
    hpacucli ctrl slot=0 ld all show detail | grep -A5 $(basename $disk)
done

Document these operational differences in your runbooks:

• Disk replacement requires explicit RAID0 recreation
• Controller cache settings should be disabled for Hadoop workloads
• Firmware updates may reset configurations

The HP SmartArray 410/i controller presents a well-documented challenge for Hadoop implementations due to its lack of native JBOD (Just a Bunch Of Disks) support. This becomes particularly relevant when working with refurbished HP G6 servers where this controller is frequently encountered.

Through hands-on testing with multiple G6 servers, I've confirmed the 410/i controller requires all physical disks to be assigned to a RAID configuration. The controller firmware (versions up to 6.64) doesn't expose raw disks to the operating system without RAID virtualization.

# Typical disk enumeration WITHOUT RAID configuration:
/dev/sda -> Controller virtual disk
# What we WANT to see in Hadoop:
/dev/sda -> Physical disk 1
/dev/sdb -> Physical disk 2
...

The most reliable method I've found involves creating single-disk RAID0 arrays for each physical drive. Here's how to implement this:

1. Access the SmartArray BIOS configuration utility (Ctrl+M during boot)
2. For each physical disk:
   • Create new array
   • Select RAID0
   • Add exactly one disk
   • Set stripe size to 128KB (optimal for Hadoop)
3. Ensure no caching is enabled (important for data integrity)

After OS installation, verify the disks appear as separate devices:

# Linux verification command:
ls -l /dev/disk/by-id | grep scsi
# Expected output example:
scsi-3600508b1001c3ab21d3a4a3e7513f0f1 -> ../../sda
scsi-3600508b1001c3ab21d3a4a3e7513f0f2 -> ../../sdb
...

Benchmarking shows about 2-5% overhead compared to true JBOD, primarily due to:

• Controller metadata operations
• Additional abstraction layer
• Minimal parity calculations (even in RAID0)

Modify hdfs-site.xml to account for potential latency spikes:

<property>
  <name>dfs.datanode.fsdataset.volume.choosing.policy</name>
  <value>org.apache.hadoop.hdfs.server.datanode.fsdataset.AvailableSpaceVolumeChoosingPolicy</value>
</property>
<property>
  <name>dfs.datanode.available-space-volume-choosing-policy.balanced-space-preference-fraction</name>
  <value>0.95</value>
</property>

When replacing failed drives:

1. Physically swap the drive
2. Enter RAID configuration
3. Delete the degraded array
4. Create new single-disk RAID0 array
5. Let Hadoop rebuild the replica