Lucy Baldwin, 123RF

A closer look at hard drives

Disco Mania

Article from ADMIN 15/2013

By Federico Lucifredi

We continue our exploration of the world of hard drives – both solid state and spinning varieties.

In the previous issue, I set down some history and the basic hard drive layout and operation background as a prelude to fully diving into the subject in this second part of my series. Resuming from where I left off, I'll try find out everything that my laptop knows about its internal drive (Figure 1).

Figure 1: Intel SA2M080G2GC, an Intel 320 second-generation SSD, being tested on a 3Gbps SATA 2 bus.

I have an 80GB Intel 320 SSD, performing remarkably close to its specified sequential read rating of 270MBps [1], but it is the second-generation drive's write performance that demonstrates the significant benefits of the TRIM [2] extension, enabling an SSD to distinguish a true overwrite operation from a write onto unallocated free space. Because a drive's logic has no insight into filesystem structure, these two operations were previously indistinguishable, needlessly degrading SSD write performance. The TRIM option enables the filesystem to notify disks of file deletions – resolving this problem in most configurations not involving RAID, which is still negatively affected.

The /etc/fstab file shows that this partition is installed with Ubuntu 12.04's default ext4 filesystem, which is

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