Linda, Please tell us which kernel version you have and include the dmesg output. Port multiplier support is generally working in 2.6.26 (and later releases) for several drivers. PM support was added after 2.6.20. Where did you find 350MB/s theoretical? Link is 8b10b encoded. So it's 10:1 of bits to bytes conversion of link rate. 3Gb/s --> 300MB/s in theory. For MB/s, it depends on the SATA controller. Don't expect more then 225-235 MB/s per port. At least one sata_sil3124 chip (3126?) is buggy and won't do more than 120MB/s read for all ports (170 MB/s write). See linux-ide archives for discussion on this. On Feb 8, 2009 1:08 PM, "Linda Walsh" <lkml@xxxxxxxxx> wrote: Is there something different, from normal disk-access, that I need to do to access hard disks beyond '1', on a port-multiplier? I thought I remembered reading the port multiplier support was working for many SATA and SATA RAID controller capable chipsets, including the Sil 3124. I picked up a 2-Bay external SATA enclosure that I'm trying to access in (what I thought) was the simplest mode: "JBOD". However, when I boot, I am only seeing the first hard disk. Experimenting, I tried a single hard disk in both positions -- one position let me see the disk directly (as though it was a direct, str8-thru connection), the other position showed up detected by the boot BIOS as a 7MB HD by some unrecognized vendor. In linux, I'm able to access and use the hard disk when it appears 'str8-thru', but linux sees nothing concerning the 7MB pseudo HD. Is my expectation that the driver would simply recognize the external enclosure by whatever I had the external enclosure set to, too optimistic? Do I need to run some special util to setup the disks in JBOD mode? I guess I thought I only needed to worry about 'special utils' if I was using the disk-pair in a RAID config (0/1)... It seems there should be a linux util to manage the "container", 'sil57xx' -- I take it is not used for RAID-only config? My ultimate aim is to use it in a RAID-0, mirror config (my luck with SATA disk drives has been abysmal, of late (*sigh*)). Anyone with any real-world experience about when the 3Gb SAS starts to become a bottleneck? I know that theoretically, it could support a hair over 350MB/s if there was no overhead, which would reliably only support 2 hard disks at full speed (assuming ~120MB/s max linear read speed/disk). Does that jive with people's real-world experience? I.e. port-multipliers can provide full throughput for 2-HD's but not likely 3? Should I be looking for an sil57xx program somewhere (the box contained a mini-CD, but it looks like a driver for an older kernel (2.6.9). Not so sure about it's usefulness in my setup. Thanks, -linda -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
