SATA III SSD drive on IDE controller - Runs in UDMA 6 is OK but slow transfers 80MB/s - expect 133MB/s

Question

I have bought a OCZ Agility 3 SSD drive to build into my ASUS laptop. Because the drive is a SATA (III) drive and the laptop has only IDE connectors, i use a Fevi/Apple Second drive Caddy to put it into the DVD drive bay of the laptop. Maybe you will ask me, "Why you want to that?". I will explain that question later.

Okay, that is working fine but the speed is some low, 80MB/s read and 45MB/s write. I know it has something to do with the connection but this is not what i expected. Because the IDE connection can handle up to 133MB/s and the OCZ drive is very fast (up to 525 MB/s max read), i expect that the result will be the 133MB/s and not 80MB/s. It is running on XP in UDMA 6 mode, so transfer speed must be 133MB/s or am i wrong?

Has this something to do with the controller in the Fevi Second drive caddy or am i missing something else? Has somebody an explanation to this or what can i do to get the full 133MB/s.

I bought this baby to get the maximum speed because IDE SDD versions are slow.

System info: ASUS A7D - AMD Turion 64 - 2GB - Windows XP Prof

Answer 1

The IDE interface is not nearly efficient enough to transfer at peak speed anywhere close to 100% of the time. Also, the interface is strictly command/response with no pipelining, so the time it takes to send a command, process that command, and process the response before issuing the next command all counts against the transfer rate.

Also, the translation adds overhead. While data is being translated, it's not being sent over the interface. Any added operation latency increases the time it takes to complete a transfer, reducing the effective transfer rate.

The mystery, I think, is why your write speed is so much less than your read speed.

Answer 2

That is the theoretical speed, but my experience has taught me that it won't reach that speed. Basically, you have nice throughput for an IDE. If you want something faster, then I'm afraid you'll need to grab a SATA controller.