Drive Imaging with dd

[Kareem Shehata]

Hey everyone,

I'm trying to image the XP partition on my laptop using Knoppix and an
external 1394 drive.  I've gotten both drives up and running, and checked
that both drives are running at full speed using hdparm:
root at ttyp0[knoppix]# hdparm -t /dev/hda

/dev/hda:
 Timing buffered disk reads:  64 MB in  3.19 seconds = 20.06 MB/sec
root at ttyp0[knoppix]# hdparm -t /dev/sda

/dev/sda:
 Timing buffered disk reads:  64 MB in  2.87 seconds = 22.30 MB/sec
root at ttyp0[knoppix]# hdparm /dev/hda

/dev/hda:
 multcount    = 16 (on)
 I/O support  =  1 (32-bit)
 unmaskirq    =  1 (on)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 nowerr       =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 4864/255/63, sectors = 78140160, start = 0
 busstate     =  1 (on)


When just dump the files directly from one drive to another, the
performance is spot on:
root at ttyp0[test]# dd if=/dev/hda1 of=shuttlepod.hda1
2260624+0 records in
2260624+0 records out
1157439488 bytes transferred in 64.225880 seconds (18021388 bytes/sec)

But the moment I stick gzip in the middle, is slows down by at least half:

root at ttyp0[test]# dd if=/dev/hda1 | gzip -1 > shuttlepod.hda1.gz
2563337+0 records in
2563336+0 records out
1312428032 bytes transferred in 203.288912 seconds (6455975 bytes/sec)

Any ideas on how to speed this up?  I've played with block size and
compression levels, but I can't seem to do better than 10M/s.
BTW: Anyone looking for motivation, my company is mainly a microsoft shop
at the moment.  Ghost doesn't support 1394, and our laptops have USB1.1
only.  Imaging used to be a pain (e.g. > 3 hours).  Not only would
efficient imaging allow me to install linux on my laptop, it would prove a
valuable tool.
Cheers, and thanks in advance,

Kareem

-- 
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      kareem-d+8TeBu5bOew5LPnMra/2Q at public.gmane.org   -   Kareem Shehata   -   416-676-6611
 --------------------------------------------------------------------
  The highest use of capital is not to make more money, but to
  make money do more for the betterment of life.
    -- Henry Ford (1863 - 1947)
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