I recently came across an interesting quirk that I had tasked myself with investigating and figuring out. I had a couple older model Samsung SSD’s which, ran in conjunction with a PERC H730 controller. Unfortunately, as soon as the 1GB controller cache was full, they tumbled from their 500 MB/s design limitation (SATA-3, 6 Gbps) down to something like 30-40 MB/s, which is a horrible performance value for that hardware.
Unaware of the actual reason for this, I started to poke around in the controller, switching between RAID and non-RAID (HBA-mode), retesting, and turning the controller cache on and off. But nothing really helped; they remained slow.
As part of poking around I they tried a ATA Secure Erase procedure on one of the disks. The procedure requires 2-3 commands and is described excellently in the Thomas Krenn-Wiki.
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