[CentOS] slow usb hard disk performance.

[William A. Mahaffey III]

Robert wrote:

> Bryan J. Smith wrote:
>
>>Robert <kerplop at sbcglobal.net> wrote:
>>  
>>
>>>    for dir in bin boot etc home initrd lib lost+found misc
>>>opt root \
>>>               sbin selinux srv tftpboot \
>>>               usr var ; do
>>>      find /$dir -depth -print0 | cpio --null -pmd $UD/$DT
>>>      echo `date` Completed: /$dir >>$PF
>>>    done
>>>    
>>>
>>
>>That's not a good benchmark.  You're adding the overhead of
>>inode/tree traversal and all sorts of other factors.  You're
>>easily cutting performance by 2-3x over.
>>
>>Since USB 2.0 EHCI is capable of only 60MBps (480Mbps)
>>theoretical, and Intel openly admits that only 30MBps is
>>realistic, 8.8MBps is not unreasonable for this command.
>>
>>Try a "raw" dd from /dev/zero, that is at least 2x your
>>memory:  
>>  dd if=/dev/zero of=(some file) bs=8M count=1000
>>
>>Or consider a bonnie benchmark.
>>  
>>
> I wasn't complaining, Bryan, simply responding.  Actually, having 
> moved from a DAT-2 drive to the USB-connected disk, I'm happy as a pig 
> in sh*t to be able to backup the whole thing unattended and have a 
> reasonable expectation that the resulting wad of crud is good! (I'm 
> still gonna burn /boot, /root, /home and /etc to DVD once a month, 
> though.)
> Have a great day!
>
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>  
>

19 GiB in 36 minutes, I wouldn't be complaining either :-). I'm using 
DDS-2 & 3, & they are MUCHO slower .... I do also backup across my 
network to a sorta-spare HDD on another box, but use the DAT tapes for 
remote storage. I might need to look into a firewire/USB disk for that 
at those speeds :-).

-- 
	William A. Mahaffey III
---------------------------------------------------------------------
	Remember, ignorance is bliss, but
	willful ignorance is LIBERALISM !!!!

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