All Posts by Date or last 15, 30, 90 or 180 days.
also by Lloyd: diglloyd.com photography and WindInMyFace.com
Thank you for purchasing through links and ads on this site.
OWC / MacSales.com...
diglloyd Deal Finder...
Buy other stuff at Amazon.com...
Up to 1527MB/s sustained performance
Handpicked deals...

$6299.0 $4199
SAVE $2100


Sony A7R IV


Please order through this ad, thanks!
Ordering through BH Photo email notice will not give me credit and you know my review will be good!
Buy at B&H via site links to support Lloyd’s reporting!
√ B&H Photo PAYS THE SALES TAX FOR YOU More info...

Reader Question: DiskTester and OS X Cache

Reader Frank W writes:

Do DiskTester files land in a system (or other) cache?

MPG: DiskTester bypasses the OS X unified buffer cache so that all its tests are actually reading and writing to the drive. This is mandatory for any meaningful results.

The drive (HDD, SSD) or a controller card might have its own cache; this is all “the drive” and is necessarily part of the test.

The DiskTester fill-volume test is useful for characterizing drive performance, whatever the type of drive.

DiskTester fill-volume produces output that can be pasted into a (supplied) Excel graph template so that volume performance can be interpreted at a glance (“volume”, not “drive” — a single drive or multi-drive RAID or an SSD or whatever is tested as a file system volume).

  • For hard drives, the graph shows how performance declines across the volume (see The Fastest 2TB Volume is on a 4TB Drive and related articles). It also shows if there are any oddball irregularities, which could indicate a marginal drive.
  • For solid state drives (SSDs), the graph makes any performance breakdowns or irregularities visible.
  • For RAID or any other type of device, the same ideas apply.

For a Fusion drive, the graph below makes clear the abrupt loss of performance when the SSD fills up.

Write and read speed of 256GB 2nd batch (512GB total) on 480GB SSD + 2TB Fusion volume

MacPerformanceGuide.com

diglloyd.com | Terms of Use | PRIVACY POLICY
Contact | About Lloyd Chambers | Consulting | Photo Tours
Mailing Lists | RSS Feeds | Twitter
Copyright © 2019 diglloyd Inc, all rights reserved.
Display info: __RETINA_INFO_STATUS__