Mobile Hard Drive speed question

[dcalfine]

Hey guys,
I'm going to be buying a mobile (2.5") hard drive to put in an enclosure, and I want to have the fastest available to me, so I have some questions:

1. What would be faster, a 7200RPM drive or a 5400RPM drive with perpandicular recording?

2. How much faster, if at all, is ATA6 vs SATA

Thanks,
DC

 

[FITCamaro]

7200 rpm

SATA. Not because its faster on the drive. You're limited by the connection type. If its USB to USB, it'll be the same for the most part. But if its eSATA, then the SATA drive has the win because eSATA is full SATA 3.0 speed. Of course you need a motherboard with an eSATA port. If you don't have one, just get a PATA drive with USB enclosure. Don't know if theres a price difference between PATA and SATA on mobile drives but if there is it isn't worth it for USB.

 

[dcalfine]

I would rarely be using it with USB. Mostly FW800 and occasionally FW400. The enclosure that I'm getting supports all three, but not ESATA.

What speed benefit do you get from the perpendicular recording on a 5400RPM if it's not faster than a 7200RPM without it?

 

[maury73]

FW400 is 20% slower than USB and FW800 rarely reaches 55-60MB/s with HDDs (under linux, with Windows it's even worse): it has much protocol overhead because it's optimized for continous regular data streaming, not for burst transfers like HDD does.

Very little speed improvement for perpendicular recording: it is intended for raising storage density, not speed, and rotational latency difference between 5400 and 7200 is very noticeable.
Read the optimum THG reviews on perpendicular, they explain all.

 

[CompTIA_Rep]

Just get a 7200rpm PR hdd in SATA.

Solves that issue

 

[maury73]

Good advice: can't do nothing for sustained speed due to USB/FW bandwidth limitation, so go for a 7200 that has lower access times, this will speed up things.

 

[dcalfine]

Comptia_Rep, no such thing exists in a 2.5" form factor

and Maury73, I'm using a Mac

well, everyone, thanks for your help, but I still don't understand how much faster SATA is than ATA6

 

[FITCamaro]

SATA isn't really faster than PATA. Theres been things like NCQ (Native Command Queueing) that help optimize the drive and increase speed but both PATA and SATA are limited by the rotation speed of the drive.

For instance, if Western Digital made the Raptor in PATA as well as SATA, there would be little difference between the two.

 

[CompTIA_Rep]

Comptia_Rep, no such thing exists in a 2.5" form factor

and Maury73, I'm using a Mac

well, everyone, thanks for your help, but I still don't understand how much faster SATA is than ATA6

Um yes. They are using PR in 2.5in hdds. Thats how they are getting the drive size up there, such as the 160gb drives. Hitachi makes some I believe.

 

[maury73]

Mac OS X transfer speeds on USB and FW are similar to linux (it's unix based).

Given the same HD unit there is absolutely no difference in speed between the SATA and PATA versions: they are simply data two different interfaces and have nothing to do with the drive transfer rate and access time.
The fastest drives available in PATA reach a maximum of 60MB/s sustained read speed in the first quarter of the surface, that is about half the bandwidth (133MB/s) of ATA6.

Only on highly optimized SATA units you can see a small improvement due to Native Command Queueing, because the drive performs seeks moving the heads as less as possible, but you can gain a 5-10% more speed only in multithreaded applications or with frequent access to very small files and besides, you will notice increased latencies in low load applications.