On Monday, 12 May 2025 23:34:36 British Summer Time Frank Steinmetzger wrote: > Am Wed, May 07, 2025 at 09:18:16AM +0100 schrieb Michael: > > On Wednesday, 7 May 2025 00:30:34 British Summer Time Dale wrote: > > > […] > > > I ran a hdparm test. I wanted to see as accurately as I could what the > > > speed was. I got this. > > > > > > > > > > > > root@nas ~ # hdparm -tT /dev/sdb > > > > > > /dev/sdb: > > > Timing cached reads: 7106 MB in 2.00 seconds = 3554.48 MB/sec > > > > These are rather pedestrian ^^^^ but I do not have any drives as large as > > yours to compare. A 4G drive here shows this: > > > > ~ # hdparm -tT /dev/sda > > > > /dev/sda: > > Timing cached reads: 52818 MB in 1.99 seconds = 26531.72 MB/sec > > Timing buffered disk reads: 752 MB in 3.00 seconds = 250.45 MB/sec > > > > That's an order of magnitude higher cached reads. > > So you have a faster machine, possibly DDR5.
Not sure if its faster, but it only has DDR4. > Dale’s NAS is an old build. I didn't know with certainty what PC it was connected to at the time. > That’s why it’s called cached. > > From the manpage of hdparm: This measurement [of -T] is essentially an > indication of the throughput of the processor, cache, and memory of the > system under test. This displays the speed of reading directly from the > Linux buffer cache without disk access. > -------------------^^^^^^^^^^^^^^^^^^^ You are right of course, thank you for point this out. I was wondering if the cached speeds may have been affected by the drive spinning down, but not spinning up fast enough when the test starts and this affecting the reading, or a bad cable. The difference in speed looked too high to me and I was looking for anything pointing to a bad connection between the drive and the PC.
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