Comments on: Why Does Software Assume Hardware is Reliable?

By: bob

bob — Thu, 28 Feb 2008 01:57:17 +0000

FireWire vs. USB 2.0 - Architecture

FireWire, uses a “Peer-to-Peer” architecture in which the peripherals are intelligent and can negotiate bus conflicts to determine which device can best control a data transfer

Hi-Speed USB 2.0 uses a “Master-Slave” architecture in which the computer handles all arbitration functions and dictates data flow to, from and between the attached peripherals (adding additional system overhead and resulting in slower data flow control)

FireWire vs. USB 2.0 Hard Drive Performance Comparison
Read and write tests to the same IDE hard drive connected using FireWire and then Hi-Speed USB 2.0 show:

Read Test:

5000 files (300 MB total) FireWire was 33% faster than USB 2.0
160 files (650MB total) FireWire was 70% faster than USB 2.0
Write Test:

5000 files (300 MB total) FireWire was 16% faster than USB 2.0
160 files (650MB total) FireWire was 48% faster than USB 2.0

By: bob

bob — Thu, 28 Feb 2008 01:52:28 +0000

The best solution is to do a raid 5, it detects if one of your drives is failing then it backs up to one drive that is kept free of info. The more drives you add the better the ratio is. usb spends 30 some % of its info saying things like, is there anything new plugged in yet? constantly! or it keeps info about the files it is transferring so most of the bandwidth is lost just in it being usb. E-Sata is where it’s at.

By: eric

eric — Wed, 26 Sep 2007 06:44:32 +0000

Drive manufacturers use “giga” to mean 1,000,000,000 rather than 2^30. This works out to 465.6 GB for a 500 “Gigabyte” drive. There’s probably some extra sectors due to drive geometry, so that’s why you only get 465.8. They aren’t really lying, just using different units then the rest of us because it makes their drives sound bigger.

By: mind

mind — Tue, 25 Sep 2007 16:16:08 +0000

when you take apart the enclosures, there’s just a normal eide or sata drive in there. you could reuse your old enclosures if you still want firewire.

storage is expected to have fast performance, which is why it assumes no errors. i really think there’s a market for a media filesystem that makes different assumptions about storage, like that it doesn’t need every last drop of performance, can tolerate errors, does raid-style redundancy with multiple drives, can have new drives added to it (or removed), etc.

By: dgurba

dgurba — Tue, 25 Sep 2007 16:03:03 +0000

How is the drive size wrong?

Most drives say they are 500GB or 150GB and they really are … but when you format a drive a portion of the harddrive becomes occupied by system allocation tables and formatting overhead (journals, etc.). So I guess I’m asking did Lacie really give you a 465.8GB drive (in which case I’d be pissed!! :P) , and was that drive like 430GB after formatting it?? …

I’ve never owned a Lacie … but might be good to know about these small typos

By: Farialima

Farialima — Sat, 01 Sep 2007 07:15:29 +0000

In each case, the Mac got thrown into a completely confused funk because the drive didnâ€™t respond quickly enough or at all.

I think that I have experienced the same issue with LaCie external HD. I was able to recover the disk by reading them with a Windows machine. It would basically “fix” them — and then, after using them on the Mac again, I would start having the same issue again.

So just a hint if those drive have data you’d like to recover: try reading them with a Windows machine

By: bob

bob — Thu, 30 Aug 2007 15:55:11 +0000

Trust me, USB 2.0 won’t help. If the drive flakes out, it’ll still wedge your Mac. It’s happened to me more than once with flaky USB flash drives, as well as one hard drive.

I think the problem is the bus, which has to be driven with the right signalling protocol or it will get into weird states and not be able to recover.

The least intrusive external storage I’ve seen, at least when it starts to die, is NAS on Ethernet. It’s still possible to wedge or hang, but I’ve seen it happen much less often.

By: nes

nes — Thu, 30 Aug 2007 15:39:33 +0000

..and don’t get me started with device drivers. Either hardware and operating systems are messed up or device driver programmers should be shot. How else can you explain constantly messing up a program that consists of nothing but a simple API layer. Granted the worst culprits are bloated video and sound card drivers but I had issues with network cards, modems, printers, and so on too.

By: nes

nes — Thu, 30 Aug 2007 15:28:29 +0000

…asynchronous programming is obviously more difficult than synchronous. I guess OS programmers follow the “worse is better” philosophy.

By: Josh Peters

Josh Peters — Thu, 30 Aug 2007 15:27:26 +0000

There is likely an issue with lack of dedicated controllers too. If all of the I/O buses are on-board and the Intel equivalent of a WinModem (ie the CPU does all of the “real” work for these devices) then it makes sense for a single process to hang the rest of the system.

If you want a reliable server system run it on server hardware. The xServe uses dedicated controllers for its I/O. I would be surprised if it had the same blocking issues that USB does.