Running a system off an external hard drive - any cons ?

My laptop has only a 60GB HDD, and as I dual boot, I'm a bit starved for space.
I have an external 400GB HDD, and my laptop apparently supports booting from USB, so I was considering using the external HDD to run an OS from.

Any cons ?

Also, say I run OS from an external 2.5 HDD housed in an aluminium enclosure.
Will it be cooler than the internal HDD of the laptop ?

EDIT: Jalf has alerted me to "external drives slow" (even in througput) myth
http://www.hanselman.com/blog/VirtualMachinesAndExternalHardDriveThroughput.aspx.

 

Other then you'd be killing your external?

It would take 5 minutes to load up windows?

Programs would run super slow, since it's a usb drive and not directly connected to the pc?

If you accidentally got disconnected, your windows install would be fubar'd?

Other then that, I see no problems.

 

As I unfortunately learned recently, some external hard drives are painfully slow (about 15-20MBps transfer rate). However, I think that will only really hurt the start up times since most of the time after boot you'll run off of RAM anyways.

I'd put the least used OS on the second hard drive, but keep your main OS in the laptop.

As far as the cooling goes, that really depends on the case but I'd expect similar temps (mid 30s C). Nothing great, but it isn't bad.

 

That is weird that it is slower, because my firewire 10,000rpm is faster then my internal, and all I do is run programs off it. I had Linux on it, but I decided to not use it recently.

 

Usb supports:

A Hi-Speed rate of 480 Mbit/s (60 MB/s).

Sata 2 hdds support:

Soon after SATA's introduction, enhancements were made to the standard. A 3 Gbit/s signalling rate was added to the PHY layer, offering up to twice the data throughput. Like SATA 1.5 Gbit/s, SATA 3.0 Gbit/s uses 8B/10B encoding, resulting in an actual data transfer rate of 2.4 Gbit/s, or 300 MB/s.

300 mbs versus 60? Or if you have sata 1, 150 versus 60?

The good news is games wouldn't be affected.

Firewire:

The full IEEE 1394b specification supports optical connections up to 100 metres in length and data rates all the way to 3.2 Gbit/s. Standard category-5 unshielded twisted pair supports 100 metres at S100, and the new p1394c technology goes all the way to S800. The original 1394 and 1394a standards used data/strobe (D/S) encoding (called legacy mode) on the signal wires, while 1394b adds a data encoding scheme called 8B10B (also referred to as beta mode). With this new technology, FireWire, which was already slightly faster [6], is now substantially faster than Hi-Speed USB.

But people should be careful to read that...

This is firewire 800. Firewire 400 runs theoritically slower then USb 2.0

FireWire 400
A 6-Pin FireWire 400 connector
A 6-Pin FireWire 400 connector

FireWire 400 can transfer data between devices at 100, 200, or 400 Mbit/s data rates (the actual transfer rates are 98.304, 196.608, and 393.216 Mbit/s, ie 12.288, 24.576 and 49.152MBytes per second respectively). These different transfer modes are commonly referred to as S100, S200, and S400. Although USB 2.0 can theoretically operate at 480 Mbits/s, tests indicate that this speed is rarely attained. This is possibly caused by the client-server architecture of USB, as opposed to the peer-to-peer network operation of FireWire, and the support for memory-mapped devices in the latter, which allows high-level protocols to run without forcing numerous interrupts and buffer copy operations on host CPUs.[5]

If you're using a newer firewire device, it may have that technology and may be able to process speed at 3.2 Gb.

It would be faster then sata 2.

To the OP: If you don't want to pay the obscene prices for notebook hdds (don't blame ya), you could get a $30 firewire enclosure, get a cheap 120 gig hdd, and put it in the enclosure, and connect it to a firewire, and your hdd will possibly run as fast, or faster, then sata 2.

That's IF you have a firewaire connection.......

Now as to why firewire is dying? Probably the same reason that Mcdondals is popular, Bose is the biggest speaker system name, monster cables are the biggest, and people randomly decide to jump off cliffs. We don't need to explain this do we?

 

Note: your laptop supports booting up the Windows on your HD from a USB device, but no machine to date supports booting up a Windows on your USB from your USB, because Windows disables USB device support during its launch process. So your idea would not work.

 

zellio, most firewire enclosure are firewire 400.
The laptop firewire ports are firewire 400 ( I bileive only the macbooks have 800).
Also, I was under the impression thta firewire 800 was only twice as fast as 400.
Max rate of 800Mbits/sec.

Budding, man windows is retarded.
But since I use linux, I'm still good

Nicolas41390, how did u boot off a firewire connection ? My bios only had a "boot off USB" option, no option for boot off firewire.

 

that is true, but google and you will see you can edit the registry to get windows to boot from usb hdd.

I've managed to create a bootable usb drive. Even compressed xp to fit into a 1gb pendrive.

There is a lot of cons to this, and I don't suggest booting off the usb hdd. I've only done it for testing. Second of all when I done this few months ago it only works on xpsp1 and not on sp2.

On some machine I heard the bootime to windows is extremely slow because before windows is loaded, some bios is running usb at 1.0 and not 2.0. Luckily mine runs okay and takes less than a minute to boot into windows.

 

Just note USB theorectical bandwidth is 480Mbits/s (60MBytes/s) but in reality I have seen from external hard drives benchmarks is around 30Mbytes/s so this may bottleneck its performance.

Firewire 400 with its lower theorectical bandwidth of 400Mbits/s (50Mbytes/s) transfers faster than usb2 in practice.

 

An internal hard drive transfers in average at 300 MB/s., but the USB 2 max transfer rate is less than 50 MB/s. So it is much slower.
An alternative is a HD conneted via SATA to the express card slot.

 

Yes, I get the thruput is lower, but does in really matter in running an OS ?
Boot up times may indeed be slower, but in general, dont seek/access times dominate when running normal programs ?

 

I think you've got your numbers mixed up a bit.

a harddrive may transfer 300Mbit/s, but certainly not 300MB.
300Mbit/s = 37.5MB/s (which is about half of what a 7200rpm drive can do)

An internal 7200rpm drive can transfer up to roughly 70 MB per second, but no more than that.

Depends. Often, yes, the seek time is more important. If you have plenty of RAM, this may be worth trying (assuming the external drive indeed has better seek time). But the lower throughput may still be a problem. Hard to say without testing it...

 

Gracias Jalf,
Another link which debunks "external drives slow" (even in througput) myth:
http://www.hanselman.com/blog/VirtualMachinesAndExternalHardDriveThroughput.aspx

 

I've noticed that in real terms external hard drives are not too slow for accessing files, ok for playing films or music off but the transfer rate is usually significantly lower than the theoretical maximum.

I can't imagine having really useful and complex OS running off an external drive, I think it'd just be too slow to really be of any use.

 

Me neither. Although theoretically possible, the stability and reliability factor is just too big of a problem. Although if you ran DOS or any microkernel OS off an external HDD that'd be perfectly fine.