[CentOS] LVM, usb drives, Active Directory

Wed Dec 16 14:31:40 UTC 2009
Steve Thompson <smt at vgersoft.com>

On Wed, 16 Dec 2009, Chan Chung Hang Christopher wrote:

> Steve Thompson wrote:
>> On Tue, 15 Dec 2009, Scott Ehrlich wrote:
>>
>>> I have a client with a handful of USB drives connected to a CentOS
>>> box.   I am charged with binding the USB drives together into a single
>>> LVM for a cheap storage data pool (10 x 1 TB usb drives = 10 TB cheap
>>> storage in a single mount point).
>>
>> I tried doing this for fun once upon a time, using 6 1TB drives. I can
>> save you a lot of grief by suggesting that you don't think about this any
>> further. Boy is it slow. And extremely unreliable. And slow. Don't even do
>> it for backups. Did I say it was slow?
>
> Please qualify 'slow'. Was it dog slow, turtle-slow, snail-slow or
> slowaris slow?

Slower than all of those. Top write speed I could ever achieve with a 
USB-2 interface and SATA drives was 20 MB/sec with a trailing wind, and 
usually half of that, with a single stream. I even tried USB-1 for more 
laughs; 1 MB/sec on a truly good day. With multiple writers, performance 
dropped so far as to be unusable (below 1 MB/sec). And we're talking mkfs 
times in _days_. The host was a CentOS 5.2 box, 32-bit.

Steve