Mobile 2.5” Client

Hard drive manufacturers design drives that will perform well for their largest customers, or sets of customers. This is why “classes” of drives exist.

Design Expectations:

The information below is a high-level set of expectations the drive manufacturers have when designing, testing and selling “Mobile 2.5” Client” drives.

  • Power On Hours
  • Write / Read Ratio
  • Block Sizes
  • Seek Profile
  • 5 hrs / 5 days(1300 POH)
  • 60/40
  • Random
  • 80% Random / 20% Sequential

Design Details:

Even through it is known that many PC’s actually run for more than 2400 hours per year, the workload is very, very low, compared with industrial uses. This allows the drive makers to put the minimum component quality and robustness into “desktop/mobile” drives, and to perform the minimum in testing during manufacture.

For all versions of desktop/mobile drives, the firmware tuning is reflective of randomly located blocks of random sized data transfers, and for the 2.5” versions, an emphasis on economy of motion and minimized power usage, which is reflected in improved notebook PC battery life.

The table below is an excerpt from the HDSTOR Drive Comparison Table, which shows features (or lack thereof) of the different classes of drives, as well as relative performance, reliability and cost.

  • Production Screening?
  • Rated for 24/7 Use?
  • Fixed Shaft Spindle?
  • RV Feed Forward Sensors?
  • Time Limited Retry Tables?
  • Mobile Client 2.5"
  • NO
  • NO
  • NO
  • NO
  • NO
  • Workload Rating
  • Firmware Tuning
  • Performance Capabilities
  • Reliability Ratings
  • Cost
  • Mobile Client 2.5"
  • LOW
  • LOW
  • LOW

Within Mobile 2.5” Client, there are many choices serving the different types of mobile computers and external storage products. Manufacturers have different height drives, from 5mm to 15mm (15mm drives are not rated for “mobile PC” use, but are designed for stationary systems or external storage enclosures), different spin rates, from 5400rpm to 7200rpm, hybrid HDD/SSD drives, and even new offerings just for tablets.

And of course, the most popular option for the best performance is a consumer class SSD, which is fast, quiet, cool and reliable, but expect to pay hundreds more for a 500GB or bigger SSD. For very small systems, such as digital signage systems, cameras or mobile DVR’s, SD cards are often used. SD cards are incredibly small, reasonably reliable, and easy for users to replace.