Re: Journal ASPs

[cmassoglia@xxxxxxxxxxx (Charlie Massoglia)]

Pete Massiello wrote:

>   I prefer a separate ASP for the Journal Receivers. The journals
>themselves must reside in the same ASP as the file that it is being
>journaled.  Think of writing to the journal receivers as a sequential
>tape.  Each time you write a record you only have to move the tape a
>little further, this is much better than writing to a tape randomly (ha
>ha, if only possible).  Well expand on that, to get better performance
>we block the writes. Now lets move that analogy to receivers & DASD.  On
>your ASP with the journal receivers, you have a set of arms that are
>ready to write the next block to disk, the arms are already in place. 
>If your receiver was "scattered" across all your disks, you would be
>contending with other writes and your arms would not be in position to
>write the next journal entry to the receiver.  By putting the Journal
>receivers to their own ASP, the disk arms are always ready to write, and
>best of all they don't have to move.  Moving of the disk arm is the
>slowest function of the disk.  
>
>   That is the reason I use a separate ASP.
>
In addition to a separate user ASP, if the drive is part of a RAID group, we
remove it from the RAID group and mirror it separately.


Charlie Massoglia, Massoglia Technical Consulting, Inc.
PO Box 1065, Okemos, MI 48854, USA
517-676-9700  Fax: 517-676-1006  EMAIL: cmassoglia@voyager.net


* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* This is the Midrange System Mailing List!  To submit a new message,   *
* send your mail to "MIDRANGE-L@midrange.com".  To unsubscribe from     *
* this list send email to MAJORDOMO@midrange.com and specify            *
* 'unsubscribe MIDRANGE-L' in the body of your message.  Questions      *
* should be directed to the list owner / operator: david@midrange.com   *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *