Date: Tue, 17 Jun 2008 13:25:40 -0400 From: Christopher Sean Hilton <chris@vindaloo.com> To: freebsd-questions@FreeBSD.ORG, roberthuff@rcn.com, chris@vindaloo.com Subject: Re: Replacing tape changer with USB disk drives. Message-ID: <E79F48F3-DA0E-489E-A6F7-75B555DC391A@vindaloo.com> In-Reply-To: <200806171540.m5HFe92o057907@lurza.secnetix.de> References: <200806171540.m5HFe92o057907@lurza.secnetix.de>
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On Jun 17, 2008, at 11:40 AM, Oliver Fromme wrote:
> Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl> 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|
dot|com
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