Hi,

 

If someone is using a mix lets say, all but one as SATA 300 drives and one drive is SATA 150... what should he expect for read/write/parity speeds?

 

Let me know if my assumptions are wrong. Also, I'm assuming parity drive to be a SATA 300 hdd.

 

Read:  If the read is from SATA 300 drive, it will be at SATA 300 read speed (ofcourse eventually limited by network speed).

Read:  If the read is from SATA 150 drive, it will be at SATA 150 read speed (ofcourse eventually limited by network speed).

 

Write: If the write is to a SATA 300 drive, it will be at SATA 300 write speed (if data transfer from outside then limited by network speed, if data shuffle between drives then limited by the lowest of the two drives or pci bandwidth).

Write: If the write is to a SATA 150 drive, it will be at SATA 150 write speed (if data transfer from outside then limited by network speed, if data shuffle between drives then limited by the lowest of the two drives or pci bandwidth).

 

Parity: this is where I'm confused... will the whole parity calculation really slow down as one drive is a sata 150?

 

Thanks.

Writing to an unRaid disk involves FIRST reading the existing contents of both the disk being written to AND the parity drive,

THEN performing the parity calculations with the new data that will be written to the disks and

FINALLY writing to both the parity drive and the data disk.

 

With that in mind, write speed will never be anywhere near as fast as reading data.  It will be much slower than the native disk read speed.

 

Joe L. 

My seagates were by default jumpered to 150 (for some STUPID reason) that I just discovered. I've since removed the jumpers letting them operate at 300 and honestly, haven't noticed much difference. With the parity on one of the mobo headers and the 3 datas on 1 promise card, the bottleneck is the PCI bus.