hard drive - How can 8 SAS lanes support 1024 disks?

According to the LSI 9207-8e specs then it supports up to 1024 disks of 6Gb/s, which I don't quite understand, when it is only an 8 lane JBOD card.

In my case, I have an HP D6000 with 70 disks as JBOD, and have excellent read/write performance.

It would be temping to think that only 8 disks of the 1024 gets full bandwidth, but just can't be the case, or is it for some reason not an issue?

If I bought the 12Gb/s LSI JBOD version, would I then get better performance when the disks are still 6Gb/s?

Answer

How can 8 SAS lanes support 1024 disks?

Using SAS expanders - each SAS channel can theoretically support 65,536 devices per link using expanders - 8 channels can easily support 1024 disks, though it would be horribly contended with 128 disks per channel.

If I bought the 12Gb/s LSI JBOD version, would I then get better
performance when the disks are still 6Gb/s?

Each channel will run at 6Gbps because that's the speed of the slowest device on the channel, so no, 12Gbps channels won't help in this case.

Out of interest how come you chose to use that controller and not the supported P888 controller from HP?

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