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SATA vs PATA

Newsgroups: gmane.linux.debian.user
Date: Mon, 27 Aug 2007

> Should I go Serial-ATA or good ol' Parallel-ATA? How do the two
> compare in terms of data throughput and Linux kernel support?

SATA-I gives 150 MB/s, SATA-II gives 300 MB/s, PATA 133 MB/s.

PATA: poor performance in general, but lousy if you have two drives on one controller. Since most boards have only 1 or two controllers, that's one or two drives. PATA bandwidth is per controller. Cable lenghth: 18", wide ribbon blocks air flow.

SATA: Being serial, each cable is point-to-point, so bandwidth is per drive. Cable length 39" (1 m).

Debian Etch has full support for SATA.

If you want to edit videos, go with SATA. If you can afford it, you may want to go with two drives and set up LVM with a stripped LV (or use raid0) to speed up the drive access.

Doug @porchlight.ca

SATA vs PATA

> SATA-I gives 150 MB/s, SATA-II gives 300 MB/s, PATA 133 MB/s.

PATA/133 was a flaky kludge. It's amazing it worked at all. Even more amazing that people got away with cables over 18" long. SATA is a far superior interconnect.

The instantaneous peak throughput of the original (four bytes wide, 33 MHz) PCI bus is 132 MB/sec. In real life you're not going to see over 90. So a SATA-II controller on a regular PCI card is bottlenecked at the motherboard slot. (So is 1000BASE-T Ethernet.) That's one reason "real hardware" RAID works better than "fakeraid." The smallest PCI Express (PCI-E) configuration should do 250 MB/sec in each direction simultaneously. A motherboard with PCI-E designed for workstations may bottleneck at the southbridge.

You'll have to do some research to find a configuration that can run two SATA-II drives simultaneously at their full data rate. You'll also have to check around to see if the Linux driver knows how to run any particular controller in SATA-II mode. And there are still lots of workstation type motherboards that only do SATA-I.

PCI-X is a kludge. I'd avoid it.

Cameron @truffula.sj.ca.us