Replacing tape changer with USB disk drives.

Christopher Sean Hilton chris at
Tue Jun 17 17:44:53 UTC 2008

On Jun 17, 2008, at 11:40 AM, Oliver Fromme wrote:

> Wojciech Puchar <wojtek at> wrote:
>>>> you must have something wrong. my USB drive gets 27MB/s. yes this
>>>> 480Mbit/s is USB isn't real, but half of it is.
>>>      I agree.
>>>      Want to take this private and help figure out what's wrong?
>>> :-)
>> i simply have no idea why it could work so slow.
> Cheap controller in the USB enclosure.  I've used quite
> a few USB enclosures in the past years, and there are
> significant performance differences.  As a rule of thumb,
> the cheaper the box, the slower it is.  Of course there
> are exceptions to that rule.
> By the way, for backup purposes I use a hot-swappable
> IDE drive frame.  The one I use is PATA (UDMA-133), but
> there are also ones for SATA.  It's much faster than
> USB and more reliable.  You can use atacontrol(8) to
> attach and detach the drive while the system is running.
> (For that to work reliably, the frame must be the only
> device on its channel, i.e. no slave, in the PATA case.)
> Best regards
>   Oliver

I get good speeds from USB but they are bursty. I have a pair of  
identical controllers and both are USB/Firewire. Both have different  
brands and sizes of disk drive. Could the drive be part of the  
problem? One is connected via Firewire and doesn't have the bursty  
speed issue. I've only got it with USB.

The poster who mentioned that I'm only looking for a backup against  
catastrophic disk failure is spot on. Offsite backup is something I'll  
work out down the road.

Chris Hilton                                   e: chris|at|vindaloo| 
                   "The pattern juggler lifts his hand; The orchestra  
       As slowly turns the grinding wheel in the court of the crimson  
                                            -- Ian McDonald / Peter  

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