i rma the adata and i rechecked both silicon power ace 55 1tb SP001TBSS3A55S25 i get from both read at around 380 MB/s on every machine i tested. adaptec controller intel ich controller amd you name it
Misalignment can certainly cause the slow read that the OP describes.
There was also a recent topic wherein partitions were misaligned during install. A solution was to use gpartedspecifically to resize the affected partitions (just a little) so that they found better boundaries.
Use the kernel´s "O_DIRECT" flag when performing a -t
timing test. This bypasses the page cache, causing
the reads to go directly from the drive into hdparm's
buffers, using so-called "raw" I/O. In many cases,
this can produce results that appear much faster than
the usual page cache method, giving a better indica‐
tion of raw device and driver performance.
unfortunatelly i tried --direct too. only when there is some io load the hdparm score changes
i tried two sp ssds and one adata all read below 400MB/s
it is either deliberatelly done by SM2258XT controller so you will not be able to raid a few of these chip ssd OR the ssd flash chips are ■■■■
There is a difference between /dev/sdv and /dev/sdv1. If the first partition is aligned correctly, you would get better results, what the discussion on the ArchForum above proves. It’s about the start sector or “Partition Starting Offset”.
So the first partition should start at ~1.5K, commonly used 2048, also 4096 improves read/write on SSD’s. That is not a big secret.
i saw that video already. we don’t care about write speed since the ssds will be used on a raid array , we care about READ speed. ssd read fast unless there is something wrong with the controller (i assume silicon motion firmware is buggy) OR crappy flash chips. it this case write speed suffers more.
tha adata su650 that i sent back had the same controller, better flash chips but same low READ speed.
in windows both drives work as expected. not as fast as a samsung but ok. again my problem is slow READ speed