After expanding an existing disk array on a Linux file server, a systems administrator observes reduced performance during write operations. The original configuration consisted of four disks managed by the server's hardware controller, and a fifth disk was introduced to enhance storage capacity. What is the most probable cause of the observed decrease in write operation speed following the expansion?
The recent disk added to the server is defective, causing a delay in the array's ability to write data effectively.
Suboptimal cable quality is causing a bottleneck in data transfer between the controller and the disks.
The overhead of parity calculations is higher now with the additional disk, slowing down the overall write performance.
The block size of the array is not properly configured for the number of disks, leading to inefficient write operations.
The addition of an extra disk into a RAID 5 array increases the complexity of the parity computation for every write operation. Since RAID 5 needs to update the parity information across the drives for data protection, it inherently suffers from write penalties. This can become more pronounced as the array extends, due to the added overhead of handling the parity calculations across an additional disk. The SATA protocol for connecting disks to the controller is not specified in the question, and while degraded cables or faulty hardware could cause slowdowns, they don't directly relate to the expansion of the array, thus are less likely the primary cause of the issue.
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