Re: Disk & Controller questions -- MIDRANGE-L


One clarification.
All AS/400 disk units are "striped", regardless of protection used.
This is a function of SLIC to scatter objects across different drives to
improve perfrmance.

    Alexei Pytel




                                                                                
                   
                    Larry Bolhuis                                               
                   
                    <lbolhuis@arbsol.co       To:     MIDRANGE-L@midrange.com, 
Dan Bale            
                    m>                         <D.BALE@handleman.com>           
                   
                    Sent by:                  cc:                               
                   
                    owner-midrange-l@mi       Subject:     Re: Disk & 
Controller questions         
                    drange.com                                                  
                   
                                                                                
                   
                                                                                
                   
                    05/16/2001 06:32 PM                                         
                   
                    Please respond to                                           
                   
                    MIDRANGE-L                                                  
                   
                                                                                
                   
                                                                                
                   



The 6501 supports two Arrays of external disks. It has two ports one for
each array.  The RAID is supported in the array. Since MIrroring is
handled by OS/400, Yes it will support that.

Mirroring is Mirroring. I think it is sometimes called RAID 1. They are
not stripped in that config as they are completely mirrored.

The different kinds of mirroring just provide better protection. Drive
level protects only against drive failure. IOP level means the mirrored
pairs are on different IOPs so a failure of an IOP does not stop the
disk subsystem. (Depending on what else is on the IOP you may still be
in trouble).  BUS level means the mirrored pairs and the IOPS are on
different system buses so theoretically even a bus failure could be
withstood. (Again depends on which bus failed and what else is on it.)

Concurrent maintenance support means you can stop a 'dead' disk, pull it
out, replace it, power it up, and rebuild it all while the system is up
and running.

 - Larry

D.BALE@handleman.com wrote:
>
> Regarding the 6501 controller (fwiw: on a V3R7 9406-510 in an expansion
unit):
>  - Does the 6501 support RAID protection?
>  - Does the 6501 support mirrored protection?
>  - The AS/400 System Handbook says that "One #6501 can support two 9337s
or
> 2105s".  We have four 9337 drives we'd like to add (they're actually
EMC(2)
> equivalents).  Do they mean two 9337 *drives* or two 9337 disk array
> subsystems?  Do the four 9337 drives make up one disk array subsystem?
(Note
> that this 6501 question is for a different system than the one I was
referring
> to in the "more DASD!!!" thread I authored earlier this week.  Thanks
Doug,
> Larry, & others!)
>
> Also, I'm getting an "education" from my boss, and his boss, and *his*
boss,
> who are all mainframe and NT wonks.  They are asking me if the mirrored
drives
> are RAID-1 and whether they are "striped" or "non-striped".  I have only
heard
> of RAID-5 protection on the AS/400.  Also, after digging around SST and
the
> system handbook, I am seeing that there apparently are different kinds of
> mirroring - controller or IOP or bus.  Do I care about this?  Are any of
these
> "better" than the others?
>
> Another quote from the system handbook: "A RAID controller is necessary
when
> concurrent maintenance support is required."  What the heck is that all
about?
>  What is "concurrent maintenance support"?
>
> Sheesh.  I shoulda gone to COMMON.  :-(
>
> TIA.
>
> - Dan
> Dan Bale says "BAN DALE!"
> IT - AS/400
> Handleman Company
> 248-362-4400  Ext. 4952
> D.Bale@Handleman.com
>   Quiquid latine dictum sit altum viditur.
>   (Whatever is said in Latin seems profound.)
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--
Larry Bolhuis                  | Cogito ergo mercari iSeries
Arbor Solutions, Inc.          |
(616) 451-2500                 |                    (I think, therefore I
buy iSeries.)
(616) 451-2571 -fax       |
lbolhuis@arbsol.com       |        #3  1951-2001
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