Ext. USB HD Choice?

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fred

What's the best choice for an external USB2 HD in the 200GB-400GB range to
be used mainly for backups?

WDC has three similar models all with 8MB onboard cache + USB2 & Firewire:

WDXB2500JB
http://www.wdc.com/en/library/dual-option/2879-001094.pdf

WDXC2500JBRNN
http://www.wdc.com/en/library/combo/2879-001073.pdf

WDXF2500JBRNN
http://www.wdc.com/en/library/dual-option/2879-001091.pdf

Which one does one get?

Are there other makes, models and sizes to consider?

What about backup or imaging software? Do any of these external USB HD
products come with a backup software(XP SP2) solution in the same league or
better than Acronis TrueImage?

Do any external USB HD products have cases which mount the drive to
specifically protect from shock/impact?

What criteria for making a choice have I missed? All the prices seem to be
in the same ballpark.
 
The best choice is probably you buy a case for about $40 ($30 or less if
you don't need both USB 2 and Firewire) and you put whatever IDE drive
you want into it. Last week, Officemax had the 320 gigabyte drive (the
WD "JB" 8 meg cache drive) on sale for $110 after a rebate. The 250 gig
drives have been on sale for as low as $79 (perhaps less, but I bought
one for $79 (after rebates)).
 
If the drive is only ever going to be in the USB box then you don't need to
get a top end drive.
IE 8MB cache & 7200RPM won't be of benefit.
So, I suggest you look at 5400RPM with smaller cache ==> lower price and
you'l never notice the drop in performance.

But... if you ever want to pull the drive out and use it in a PC then you
will likely want a 7200RPM drive...

- Tim
 
Barry Watzman said:
The best choice is probably you buy a case for about $40 ($30 or less if
you don't need both USB 2 and Firewire) and you put whatever IDE drive you
want into it. Last week, Officemax had the 320 gigabyte drive (the WD
"JB" 8 meg cache drive) on sale for $110 after a rebate. The 250 gig
drives have been on sale for as low as $79 (perhaps less, but I bought one
for $79 (after rebates)).
Click to expand...

Yes but the requirement in this situation is for a pre-packaged major
supplier solution. So the question remains...Which one? Included backup
software vs. Acronis etc.
 
Tim said:
If the drive is only ever going to be in the USB box then you don't need
to get a top end drive.
IE 8MB cache & 7200RPM won't be of benefit.
Click to expand...

The 8MB cache will help as will 7200 RPM on USB 2.
So, I suggest you look at 5400RPM with smaller cache ==> lower price and
you'l never notice the drop in performance.
Click to expand...

In many backup cases that's true.
 
What's the best choice for an external USB2 HD in the 200GB-400GB range to
be used mainly for backups?
Click to expand...
<...>
I've been using two models: a Maxtor OneTouch USB2/Firewire 250 GB and
a LaCie P3 250 GB (USB2). Speeds are about the same (I'm using via USB2),
but the Maxtor is sturdier and heavier, and can be set to spin down
after a period of inactivity. This isn't available for the LaCie so
it'll just keep on spinning unless you power it down.

Maxtor bundle Danz Retrospect Express or something, LaCie doesn't come
with backup software I think. Nowadays there's "Small Business Edition"
of the Maxtor, you might check that out.

http://www.maxtor.com/_files/maxtor/en_us/documentation/data_sheets/onetouch_ii_datasheet.pdf
http://www.maxtor.com/_files/maxtor/en_us/documentation/data_sheets/onetouch_ii_SBE_datasheet.pdf
http://www.lacie.com/download/manuals/p3_usb_hd_en.pdf


-Teemu
 
Re:

"If the drive is only ever going to be in the USB box then you don't
need to get a top end drive. IE 8MB cache & 7200RPM won't be of benefit."

**************

I'd disagree with you. USB 2 and Firewire are fast enough that they are
not the limiting factor in overall drive speed. Thus the rotational
speed and cache size are still very much relevant.

However, I would note a different point; while you can't exclude cache
size and rotational latency because it's an external USB 2 drive, the
original post stated that this drive was "to be used mainly for
backups". On that basis, one might decide to accept a 5400 rpm drive
with 2MB of cache, and save $20 to $50 on the drive.
 
Barry Watzman said:
However, I would note a different point; while you can't exclude cache
size and rotational latency because it's an external USB 2 drive, the
original post stated that this drive was "to be used mainly for
backups". On that basis, one might decide to accept a 5400 rpm drive
with 2MB of cache, and save $20 to $50 on the drive.
Click to expand...

I still use 4200 rpm which are even cheaper and quieter.
 
Re:

"If the drive is only ever going to be in the USB box then you don't
need to get a top end drive. IE 8MB cache & 7200RPM won't be of benefit."

**************

I'd disagree with you. USB 2 and Firewire are fast enough that they are
not the limiting factor in overall drive speed. Thus the rotational
speed and cache size are still very much relevant.
Click to expand...


No, Tim was very correct, USB 2.0 is the limiting factor for a disk. I
take it that you have no external drive? Certainly you have never measured
actual throughput. Free utilities like HDTach make this measurement very
easy.

The USB 2.0 buss is theoretically rated 480Mb/second (60MB/second), but
only the naive will believe that is even imaginable. It isnt. Even a fast
device cannot achieve more than about 30-32 MB/second of that (roughly
half). Presumably the idea of the buss speed is that two fast devices
could simultaneously use more of the theoretical bandwidth (but I wont take
any bets on that).

The Firewire buss is theoretically rated 400Mb/second (50MB/second), but
even a fast device cannot achieve more than maybe 38MB/second of that.
Firewire has a faster actual than USB 2.0, despite its slightly lower buss
speed.

A fast 7200 RPM drive might be capable of 50 to 60 MB/second itself, but
not when held back by a USB 2.0 or Firewire interface. USB is always the
limiting factor for a disk drive. Put your slowest drive in a USB case.

For another reference, see second paragraph at
http://www17.tomshardware.com/storage/20030411/wd_external_hd-09.html

They are able to measure 32MB/second from an external USB 2.0 drive,
but my own measurement is 29.9MB/second (with a WD 120GB disk which
approaches 50MB/second itself standalone). Which is close enough
agreement, half isnt far wrong. Certainly 480Mb/second is not even
imaginable (but marketing does tend to promote that number).
 
Wayne said:
The USB 2.0 buss is theoretically rated 480Mb/second (60MB/second),
but only the naive will believe that is even imaginable. It isnt.
Even a fast device cannot achieve more than about 30-32 MB/second of
that (roughly half). Presumably the idea of the buss speed is that
two fast devices could simultaneously use more of the theoretical
bandwidth (but I wont take any bets on that).
ROTFL


The Firewire buss is theoretically rated 400Mb/second (50MB/second),
but even a fast device cannot achieve more than maybe 38MB/second of
that. Firewire has a faster actual than USB 2.0, despite its
slightly lower buss speed.
Click to expand...

Yeah, best four hubs of that.
A fast 7200 RPM drive might be capable of 50 to 60 MB/second itself,
but not when held back by a USB 2.0 or Firewire interface. USB is
always the limiting factor for a disk drive. Put your slowest drive
in a USB case
Click to expand...


Every small factor can speedup or slowdown. Even 8X AGP speeds up, for
sure. Well, maybe like 4789 (4x) vs. 4842 (8X). If you repeat a
Benchmark for thousand Times it would make the difference bigger. But
in 24 pictures per second (swordfishes read over 100), which a human
can read it would not make a difference.

The specification for USB are true but there are other limitating
factors. e.g my Ram on the MB can read 800MB/sec but it is not even
imaginable that I could ever see something 500MB Big in one second
loaded, but the specification is again true but the system, chipset,
cpu, gfx, ALL, cannot get faster to that :-)



Kind Regards,

Daniel Mandic
 
Barry Watzman said:
Re:

"If the drive is only ever going to be in the USB box then you don't
need to get a top end drive. IE 8MB cache & 7200RPM won't be of benefit."

**************

I'd disagree with you. USB 2 and Firewire are fast enough that they are
not the limiting factor in overall drive speed. Thus the rotational
speed and cache size are still very much relevant.

However, I would note a different point; while you can't exclude cache
size and rotational latency because it's an external USB 2 drive, the
original post stated that this drive was "to be used mainly for
backups". On that basis, one might decide to accept a 5400 rpm drive
with 2MB of cache, and save $20 to $50 on the drive.
Click to expand...

You can now get ESATA external enclosures - buy a SATA interface
card with ESATA connector for ~$25 for your PC, and then the
connecting cable (@150MB/sec) is no longer an issue.

What is an issue, is how fast the backup software runs. Maybe
the software does compression of the data, before writing the
data out to disk. That might drop you to less than 10MB/sec
of data ready to go, so then all this worry about the cable
is for nothing.

If the drive were to be used as a portable file system, then
ESATA is the way to go.

If the drive is being used as a fancy tape drive, with
sequential access pattern, you might only see the full media
speed if you are doing an uncompressed sector by sector backup.
If you use Retrospect and file-by-file backup, the whole process
will be slow-as-a-slug no matter what kind of cable is used.

Here is one user's comments on some backup software choices:

http://www.wilderssecurity.com/showthread.php?t=53817

And if this backup solution is being used for a business,
having a bunch of disk drives laying about is not a good
backup strategy. Think disaster recovery and what to do if
a fire levels the business. Hire a professional who can look
at your computing resources and do it right. Or pick up a
good book and see how others do it.

Paul
 
And if this backup solution is being used for a business,
having a bunch of disk drives laying about is not a good
backup strategy.
Click to expand...

Nope, using disks for backup is a very effective strategy. Make sure that
includes offsite cycling.
Think disaster recovery and what to do if
a fire levels the business.
Click to expand...

Offsite cycling of backups.
Hire a professional who can look
at your computing resources and do it right. Or pick up a
good book and see how others do it.
Click to expand...

Yep, the experts are switching to removable HDs for backups in MANY
environments. Tape drives using flexible magnetic media are inherently
slow, unreliable and EXPENSIVE. There is no effective tape backup solution
for the small business nor soho user.
 
This discussion pertained to external drives for backup in the 200+ gig
size range. There are no 4200 rpm drives in this size range, of any
size, nor are there any 2.5" drives of any rotational speed in this size
range.
 
This discussion pertained to external drives for backup in the 200+ gig
size range. There are no 4200 rpm drives in this size range, of any
size, nor are there any 2.5" drives of any rotational speed in this size
range.
 
I have external drives and use them all the time. And the rotational
speed and cache are still relevant when using a USB 2 external drive (or
a firewire drive)
 
fred said:
Nope, using disks for backup is a very effective strategy. Make sure that
includes offsite cycling.


Offsite cycling of backups.


Yep, the experts are switching to removable HDs for backups in MANY
environments. Tape drives using flexible magnetic media are inherently
slow, unreliable and EXPENSIVE. There is no effective tape backup solution
for the small business nor soho user.
Click to expand...

I agree that tape sucks. I've wanted a tape backup system for
home use, but the cost was always prohibitive. You would think
that as time passed, someone would try to make a more cost effective
solution.

http://www.tomshardware.com/storage/20030225/index.html

At the other extreme, is something like this.
I hope this data center never floods...
http://www.tomshardware.com/newsletter/vol3/16/70tb.html

At least if you go the hard drive route, pick a method that is
volumetric efficient.

http://www.granitedigital.com/catalog/pg53_satahot-swapbackup.htm

The pictures in this manual, show how little the drive tray adds
to the basic volume occupied by a drive.

http://www.granitedigital.com/_downloadfiles/acrobat/SATA_Hot-Swap_Manual.pdf

I would try to put each day's backup on a separate drive. If
you run incrementals during the week, and a full once a week,
you may be able to buy mostly smaller drives for the
incrementals, and the larger drive for the weekly backup.
You'll still need to put away a big drive on a regular basis,
like monthly, or yearly etc.

Paul
 
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