[CentOS] slow usb hard disk performance.

Robert kerplop at sbcglobal.net
Mon Dec 5 18:04:53 UTC 2005


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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