June 13, 2024

Data Storage Tech & Networks

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Data Storage Tech & Networks Question and Answers

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Q1.Given a scenario where a company encountered a critical issue with a specific batch of disk drives from a vendor, resulting in over 30 drive failure within a single storage array over less than a week, leading to the potential for catastrophic data loss, propose an effective solution to prevent such data loss Justify your recommendation.


  1. Immediate Replacement: Swiftly replace all affected disk drives with a more reliable batch or an alternative vendor’s product to mitigate further failures.
  2. Data Backup and Recovery: Prioritize data backup and implement a robust recovery plan to ensure minimal data loss. Regularly test the backup and recovery processes to guarantee their effectiveness.
  3. Vendor Communication and Investigation: Engage with the vendor to investigate the root cause of the drive failures. This collaboration can help identify if it’s a systemic issue, ensuring that the replacement drives are not prone to the same problems.
  4. Diversify Storage Arrays: Distribute data across multiple storage arrays to reduce the impact of potential failures. This strategy enhances fault tolerance and safeguards against the catastrophic loss of data in case of similar incidents.
  5. Implement Monitoring and Alerts: Set up comprehensive monitoring systems to track the health of disk drives in real-time. Implement alerts for any anomalies or early signs of potential failures, allowing proactive intervention before a critical situation arises.
  6. Regular Audits and Quality Assurance: Conduct routine audits of hardware components to maintain quality assurance. Regularly assess the reliability of storage hardware through performance testing and stress analysis.
  7. Consider Redundancy and RAID: Employ RAID configurations and redundancy measures to enhance data protection. This can provide fault tolerance and data integrity even if individual drives fail.
  8. Contractual Agreements and SLAs: Review and revise contractual agreements with vendors to include stringent Service Level Agreements (SLAs) that ensure quick response times for replacements and support in case of hardware failures.

By combining these measures, the company can establish a comprehensive strategy to prevent data loss, respond promptly to hardware failures, and minimize the impact of critical incidents on their storage infrastructure.


Q.3. a) Let us assume we have a RAID 6 setup with 6 disks, each disk is of 350 GB, 10000 RPM and IOPS of each disk is 125, Calculate RAW IOPS and functional IOPS if there are 60% of read and 40% of write on an average. What will be read penalty in this RAID? [3]
(b) If in block there are 6 pages holding valid data in 4 pages and stale data in 2 pages, the how many read write will happen if we want to overwrite those two stale pages with 2 good pages?

ANSWER:-(a) To calculate the RAW IOPS in a RAID 6 setup, you can use the formula:

RAW IOPS=Number of Disks × IOPS per Disk

Given that there are 6 disks, each with an IOPS of 125:

RAW IOPS=6×125=750 

Now, to calculate functional IOPS, taking into account the 60% read and 40% write:

Functional IOPS=(Read Percentage×Read IOPS)+(Write Percentage×Write IOPS)

Assuming Read IOPS is the same as IOPS per disk (125) and Write IOPS is usually considered to be half of Read IOPS in RAID 6:

Functional IOPS=(0.6×125)+(0.4×0.5×125)

Functional IOPS=75+25=100 IOPS

The read penalty in RAID 6 is generally 2 since each read operation requires two I/O operations to retrieve the data (one for the data and one for the parity).

(b) To overwrite two stale pages with two good pages in a block where there are 6 pages (4 holding valid data and 2 holding stale data), you would need to perform one read operation for each stale page to retrieve the valid data, and then one write operation for each good page to overwrite the stale data. Therefore, the total number of read and write operations would be 2(read)+2(write)=4.

Q.4. A) A computer system has a system bus with a width of 32 bits and a clock speed of 100 MHz. Calculate the maximum data transfer rate of the system bus.
B) A PCI Express bus has a lane width of 8 bits and a clock speed of 5 GHz. Calculate the maximum data transfer rate of a single PCI Express Lane.


A)The maximum data transfer rate (or bandwidth) of a system bus can be calculated using the formula:

Data Transfer Rate=Bus Width×Clock Speed

In this case, the bus width is 32 bits, and the clock speed is 100 MHz. First, convert the clock speed to megabits per second (Mbps) to match the units with the bus width:

Clock Speed in Mbps=Clock Speed in MHz×Number of Bits in a Byte1 million

Clock Speed in Mbps=100 MHz×81 million=0.8 Mbps

Now, you can use the formula to find the maximum data transfer rate:

Data Transfer Rate=32 bits×0.8 Mbps=25.6 Mbps

So, the maximum data transfer rate of the system bus is 25.6 megabits per second.

B) The maximum data transfer rate of a PCI Express (PCIe) lane can be calculated using the formula:

Data Transfer Rate=Lane Width×Clock Speed

In this case, the lane width is 8 bits, and the clock speed is 5 GHz. First, convert the clock speed to gigabits per second (Gbps) to match the units with the lane width:

Clock Speed in Gbps=Clock Speed in GHz×Number of Bits in a Byte1 billion

Clock Speed in Gbps=5 GHz×81 billion=40 Gbps

Now, you can use the formula to find the maximum data transfer rate:

Data Transfer Rate=8 bits×40 Gbps=320 Gbps

So, the maximum data transfer rate of a single PCI Express lane is 320 gigabits per second.

Q.5.It is required Ito mount a file on the client machine with IP 12 34. 1.55. 100 from a server amcec.com, the folder to be mounted is /etc/homelamc with read and write permission. The folder name on the client is same as on the server. Write necessary server and client’s entries for the above Purpose .


To achieve the specified file mount, you can use the mount command on the client machine. Here’s an example entry for the /etc/fstab file on the client, assuming you’re using NFS (Network File System):

Client Entry (/etc/fstab): /etc/homelamc nfs rw 0 0

This assumes that the NFS server at IP address is exporting the directory /2023/1, and you want to mount it at /etc/homelamc on the client with read and write permissions.

Ensure that the necessary NFS client packages are installed on the client machine.

On the server side, you need to configure the NFS server to export the specified directory. Ensure that the NFS server is configured to allow connections from the client IP address.

Server Entry (NFS exports file – usually /etc/exports):


This assumes that the server is exporting the /2023/1 directory to the client with IP address with read and write permissions.

After making these changes, restart the NFS service on the server, and then you can mount the directory on the client using the mount command or reboot the client machine.

Mount Command (on client):

sudo mount -a

This command reads the /etc/fstab file and mounts all entries defined there.

Q.6. it is required to connect two clients one running Unix and another windows OS to a NAS device with NAS head connected to storage through SCSI, FC or ATA Suggest a method of connecting these clients to a NAS and give the role of each of NAS Device components in your setup.


To connect a Unix client and a Windows client to a NAS device with a NAS head connected to storage through SCSI, FC, or ATA, you can follow these steps:

  1. Network Setup:
    • Connect the NAS device to the network.
    • Ensure both Unix and Windows clients are on the same network.
  2. NAS Device Configuration:
    • Configure the NAS device to support both Unix and Windows file systems (e.g., NFS for Unix and SMB/CIFS for Windows).
  3. Unix Client Connection:
    • For the Unix client, use NFS (Network File System) to connect to the NAS device.
    • Mount the NAS storage on the Unix client using NFS commands.
  4. Windows Client Connection:
    • For the Windows client, use SMB (Server Message Block) or CIFS (Common Internet File System) to connect to the NAS device.
    • Map network drives on the Windows client to the NAS storage using SMB/CIFS protocols.
  5. NAS Device Components:
    • NAS Head:
      • Acts as the control unit for the NAS device.
      • Manages file access requests from clients.
      • Converts file requests from different protocols (NFS for Unix, SMB/CIFS for Windows).
    • Storage Connection (SCSI, FC, ATA):
      • Represents the physical connection between the NAS head and the storage.
      • Transfers data between the NAS head and the storage devices.
      • Depending on the chosen connection (SCSI, FC, ATA), the NAS head communicates with the storage subsystem.
    • Storage:
      • The actual storage devices (hard drives or SSDs) where data is stored.
      • Managed and accessed through the NAS head.
      • Provides the capacity for storing files and data.


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