He1p Required - Please??? (fwd)

[Sam Eaton]

On Fri, Aug 13, 1999 at 12:20:44PM +0200, Ian Freislich wrote:
> >
> > ccd0 65536 none /dev/da1e /dev/da4e /dev/da2e /dev/da5e /dev/da3e
> > /dev/da6e /dev/da7e
> 
> That's quite a large interleave factor. We set ours to 64k (the
> maximum block transfer size), or 128 blocks with good performance
> results. This gives the disks time to 'recover' between reads and
> writes. Your interleave factor is 32Mbytes which means 32Mb is
> written before moving on to the next disk in your stripe.

I'm interested to see this, as I have my CCD setup the same way, with
65536.  The reason I did this is due to the bit in the ccd(4) man page : 

    For random-access oriented workloads, such as news servers, a
    larger interleave factor (e.g., 65,536) is more desirable.  Note
    that there isn't much ccd can do to speed up applications that are
    seek-time limited.  Larger interleave factors will at least reduce
    the chance of having to seek two disk-heads to read one directory or
    a file.

Is this actually the wrong advice then?  Should I be using a smaller
interleave for my CCD stripe? (I'm using the stripe for the history and
overview databases)

Sam.
-- 
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Sam Eaton                  Senior Systems Manager, Pavilion Internet Plc
         "Fortified with essential bitterness and sarcasm"
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