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View Full Version : Again a Mini question: Using an external harddisk as boot device?


manchurian
Jan 26, 2005, 02:21 PM
So I read that the harddisk in the Mac Mini is pretty slow. Would it make sense to get an external Firewire Harddisk and install OS X onto the external harddisk? How high is the latency of the Firewire in general? Faster than IDE/SATA maybe?

Thanks for any information :)

rhpenguin
Jan 26, 2005, 02:55 PM
This is something im curious about too and im going to figure out by setting up a mini with some xbench lovin at my mac dealer when they get a unit in :)

ravenvii
Jan 26, 2005, 03:15 PM
Firewire (and even USB 2.0) is PLENTY fast enough for SATA drives. Firewire has a 400 MBps bandwidth and USB 2.0 has about 480 MBps. SATA has a bandwidth of 150 MBps.

So yes, getting a WD Raptor 10,000 RPM SATA drive, putting it into a Firewire/USB 2.0 enclosure and making that a bootable drive WILL make your mini alot faster.

manchurian
Jan 26, 2005, 03:29 PM
Firewire (and even USB 2.0) is PLENTY fast enough for SATA drives. Firewire has a 400 MBps bandwidth and USB 2.0 has about 480 MBps. SATA has a bandwidth of 150 MBps.

So yes, getting a WD Raptor 10,000 RPM SATA drive, putting it into a Firewire/USB 2.0 enclosure and making that a bootable drive WILL make your mini alot faster.

I'm not sure if there are such enclosures but I'm also wondering how fast those external Firewire harddisks are compared to SATA and IDE harddisks.

ravenvii
Jan 26, 2005, 03:37 PM
Yeah there are enclosures like that, I've seen them.

But that's an interesting question about the external firewire drives. But that does raise a question, if a firewire-based external harddrive is faster than a SATA enclosure-based HD, why did they bother developing SATA, instead of just going for a USB 2.0 or Firewire external standard? (Essentially having Firewire or USB 2.0 replacing PATA)?

manchurian
Jan 26, 2005, 03:44 PM
Yeah there are enclosures like that, I've seen them.

But that's an interesting question about the external firewire drives. But that does raise a question, if a firewire-based external harddrive is faster than a SATA enclosure-based HD, why did they bother developing SATA, instead of just going for a USB 2.0 or Firewire external standard? (Essentially having Firewire or USB 2.0 replacing PATA)?


http://www.addonics.com/products/enclosures/ae5idecsu2f.asp

here's such an enclosure.

Zenith
Jan 26, 2005, 03:51 PM
Firewire (and even USB 2.0) is PLENTY fast enough for SATA drives. Firewire has a 400 MBps bandwidth and USB 2.0 has about 480 MBps. SATA has a bandwidth of 150 MBps.

So yes, getting a WD Raptor 10,000 RPM SATA drive, putting it into a Firewire/USB 2.0 enclosure and making that a bootable drive WILL make your mini alot faster.

I think the correct numbers are; FireWire 400 - 400 Mbps, USB 2.0 - 480 Mbps, SATA - 150 MBps or 1200 Mbps.

In reality a good 7200 RPM external hard drive will produce speeds up to around 50 MBps, and the bandwidth for FireWire 400 is theoretically maximum 50 MBps (400 Mbps). So the hard drive could be limited by the speed of the FireWire bus, since it practically never reaches 50 MBps.

On the other hand I'd guess that you'll see speeds around 40 MBps, and that should be plenty fast enough, and much faster than the Mini's internal drive.

ravenvii
Jan 26, 2005, 03:58 PM
Ah, damn the MB and the Mb, they get me every time. :)

manchurian
Jan 26, 2005, 04:07 PM
Here are my HDTach stats from Maxtor One Touch 200GB Firewire Harddisk and my Barracuda V 120GB Harddisk:

Maxtor One Touch 200GB:
Random Access: 19.0ms
CPU Utilization: 2%
Average Read: 36.5MB/s

Barracuda V 120GB:
Random Access: 13.3ms
CPU Utilization: 4%
Average Read: 42.5MB/s

cluthz
Jan 26, 2005, 04:10 PM
Firewire (and even USB 2.0) is PLENTY fast enough for SATA drives. Firewire has a 400 MBps bandwidth and USB 2.0 has about 480 MBps. SATA has a bandwidth of 150 MBps.

So yes, getting a WD Raptor 10,000 RPM SATA drive, putting it into a Firewire/USB 2.0 enclosure and making that a bootable drive WILL make your mini alot faster.

NO!!!

SATA has 150 MBytes/sec =1200Mbit/sec
Firewire400 has 50MBytes/sec = 400Mbit/sec
USB2.0 has 60MBytes/sec = 480 Mbit/sec

A raptor is a overkill for a firewire enclosure.
A firewire400 drive will due to overhead and brigding max out at ~40MBytes/ sec. Any never ATA133 or SATA HD will go well beyond it.
USB 2.0 is a horrible chapter on Macs, it will likely max out on ~20MBytes/sec and it will be a lot slower than the internal mini mac harddrive

My two year old Maxtor 740DX 80GB ATA/100 is faster than my LaCie Extreme 250GB when connected to firewire 400....

MacNeXT
Jan 26, 2005, 04:38 PM
Maybe this interests you.

Here some xbench results of a test I did a while ago. It compares the internal 30GB 4200RPM drive of the most recent iBook to an external FW/USB2.0 enclosure with "Oxford" bridge chip and Western Digital WD800 (80GB, 7200rpm, 2MB cache).

Note that I suspect the iBook internal drive results to be similar to the Mac Mini's, cause they seem to be very built out of almost the same hardware.

Firewire


Disk Test 71.95
Sequential 61.28
Uncached Write 64.62 26.94 MB/sec [4K blocks]
Uncached Write 64.31 26.34 MB/sec [256K blocks]
Uncached Read 47.67 7.55 MB/sec [4K blocks]
Uncached Read 75.33 30.44 MB/sec [256K blocks]
Random 87.12
Uncached Write 90.18 1.35 MB/sec [4K blocks]
Uncached Write 92.19 20.79 MB/sec [256K blocks]
Uncached Read 82.58 0.55 MB/sec [4K blocks]
Uncached Read 84.26 17.34 MB/sec [256K blocks]


USB2.0


Disk Test 29.42
Sequential 18.82
Uncached Write 35.88 14.96 MB/sec [4K blocks]
Uncached Write 34.65 14.19 MB/sec [256K blocks]
Uncached Read 7.87 1.25 MB/sec [4K blocks]
Uncached Read 34.79 14.05 MB/sec [256K blocks]
Random 67.37
Uncached Write 80.72 1.21 MB/sec [4K blocks]
Uncached Write 64.92 14.64 MB/sec [256K blocks]
Uncached Read 69.51 0.46 MB/sec [4K blocks]
Uncached Read 58.15 11.97 MB/sec [256K blocks]


Internal iBook drive (4200rpm, 30GB)


Disk Test 49.17
Sequential 50.99
Uncached Write 47.69 19.88 MB/sec [4K blocks]
Uncached Write 40.58 16.62 MB/sec [256K blocks]
Uncached Read 103.12 16.32 MB/sec [4K blocks]
Uncached Read 43.21 17.46 MB/sec [256K blocks]
Random 47.47
Uncached Write 44.66 0.67 MB/sec [4K blocks]
Uncached Write 43.82 9.88 MB/sec [256K blocks]
Uncached Read 54.49 0.36 MB/sec [4K blocks]
Uncached Read 48.30 9.94 MB/sec [256K blocks]


Firewire is way faster than internal!

topgunn
Jan 26, 2005, 04:58 PM
I tested my Hitachi 7K250 7200rpm 160GB HD in an external enclosure connected to my iMac G5 via firewire 400 with Xbench's disk test. The drive continually scored in the low 70's, barely higher than the mini's stock 4200rpm 2.5" drive. I had nearly identical results when I connected it to my 3rd generation eMac via firewire however the drive scored around 130 when connected to the eMac's internal IDE bus.

Bandwidth is only one variable that needs to be considered here. While firewire is capable of supporting a fast IDE drive with little bottle neck at around 40MBps, you still have to consider latency and processor load. Both of these will be considerably higher when using a drive in an external enclosure. However, considering that the Mac mini already has very low disk scores (mid 60's according to most reports on Xbench's results comparison site), you would not be taking a performance hit by using an external drive and might actually be a bit faster. It would be nice if you just wanted more space but it would likely cause some hassles down the road.

To increase disk access and read times, you have two options as I see it. One, replace the 4200rpm interal drive with a 7200rpm drive. You can find these in 40, 60 & 80GB versions from $100-$200 dollars. According to the one Mac mini on Xbench's results comparison site with a 7200rpm drive, this would give you a disk score in the low 90's. The second option would be to use a 44-pin to 40-pin adapter to connect a standard 40-pin 80-conductor IDE cable internally to your Mac mini and route the ribbon cable into your external enclosure. Power the drive via the enclosures power supply. Of course you will lose some (ok all) of the mini's "sleekness" but your disk score should be in the upper 120's.

bigandy
Jan 26, 2005, 05:44 PM
the mac mini comes with either a 4200rpm or 5400rpm drive. replace this with a 7200rpm drive and you're sorted.

screw messing around with firewire drives. and if you're going to go external get a firewire drive, not USB2.0. the usb standard just can't handle large amounts of data over it. ever wonder why all videocameras etc use firewire?

kgarner
Jan 26, 2005, 06:03 PM
The major problem I see with this setup is that the Mini has only one Firewire port. I know that most Firewire drive offer daisy chaining, but how well does that work? Can I boot off my 7200 RPM External and plug my camcorder into the extra port on the drive and capture without dropped frames? I honestly don't know, but when I get my Mini (waiting for my tax return) I will try it out, but if anyone has any experience with this I would appreciate it.