Poster said:
Hi,
I've run out of SATA ports on my motherboard but want a new hard disk,
so I need a SATA controller card.
I've been looking at the controller cards available at one of my suppliers.
1.
http://tinyurl.com/69hqxo
2.
http://tinyurl.com/595aab
3.
http://tinyurl.com/5gnmuz
I'm a little confused between the standards, the hard disk I've been
thinking of getting is this 1 TB Samsung:
http://tinyurl.com/5vj8b8
Am I correct that to maximize that hard disk's potential I should get
the no 1. controller card above because it supports 3.0 Gb/s while the
other 2 controller cards have transfer rates of 150 MBps?
Or am I in a muddle?
Thanks all.
This one is PCI Express, and could be using a SIL3132.
You need a PCI Express x1 or larger slot, to use this.
Not all motherboards have PCI Express slots.
"Value SATA II 2 Port Controller Card - PCI Express"
http://www.overclock.co.uk/product/Value-SATA-II-2-Port-Controller-Card---PCI-Express_874.html
*******
This one has a PCI bus connector, and four SATA ports. The
main chip is likely a SIL3114. By means of firmware flashing,
the card can run in RAID or IDE mode.
"Value SATA 4 Port Controller Card - PCI"
http://www.overclock.co.uk/product/Value-SATA-4-Port-Controller-Card---PCI_876.html
*******
The third card looks to be SIL3112 based, and another PCI
card. Same story as the SIL3114, only the SIL3112 has half
the number of ports. Firmware flashing allows either RAID
or IDE mode. PCI cards are best suited to older computers,
which don't have PCI Express slots.
Value SATA 2 Port Controller Card - PCI
http://www.overclock.co.uk/product/Value-SATA-2-Port-Controller-Card---PCI_875.html
*******
The desktop PCI bus operates at 33MHz and is 32 bits wide.
The transfer rate you can expect on the bus, is 110-120MB/sec.
The bus is shared and unidirectional, so disk to disk
transfers handled by the same controller card, would be
60MB/sec read and 60MB/sec write or so.
The SIL3112 and SIL3114 also have a 66MHz option, but on
desktop computers, that is hardly ever an option. That would
be more likely found on a server motherboard. The higher clock,
doubles the bus performance. Not all PCI peripheral chips support
66MHz, but I think the Silicon Image ones being discussed here, do.
Disks have "burst to cache" performance, and "sustained" transfer
performance. The cache is used to hold short transactions.
Via the SATA interface, you can probably burst to the cache, at
a decent percentage of the SATA cable rate.
Sustained transfer, is what happens when large files are
transferred, and the cache is filled. Then, the media rate
(head rate) is the limiting step. On my current hard drive,
this is about 60MB/sec. The best SATA drives now, offer much
higher figures. (Velociraptor is 119MB/sec at the beginning
of the disk.)
For sustained transfers, there are a couple scenarios to
consider. If two disks are connected to the same card, and
you do a disk to disk transfer, then the motherboard bus
can be a limiting factor to the sustained transfer. If
one disk was connected to the Southbridge, and the other
was on the controller card, then perhaps there isn't a
bus limitation as a result. (They might use separate busses,
or the second bus may be less limiting.)
The first card of the three is least likely to limit
theoretical performance. Being on a private bidirectional bus
(with a separate 250MB/sec TX and 250MB/sec RX bus), you can
actually burst from disk to disk, without significant limitation.
My main concern then, would be the bus interface,
rather than SATA 150 versus SATA 300. You want
your controller card solution, to at least handle
the sustained transfer rate scenario, without
embarrassment. (Burst performance isn't as big
a deal.) If you own "sad old disks", then
the SIL311x cards in IDE mode, might be all
you need. If you paid good money for two
Velociraptor class drives, then that is when
you want a better bus interface on the
card (so you can go disk to disk, and move
2 * 119MB/sec data on the computer bus). The
PCI Express x1 interface makes that possible.
Paul
