Re: Guest Partition Storage Configuration

Jeff,

You are correct, IBM i sees each storage space virtual disk unit the same as a physical unit and will behave as designed and use single level storage techniques. The OS in this case is not aware that the host is also IBM i. So the best thing to do is honor it and give it several disk units to use, in my view, as small of a unit as is practical given the situation. For a 150Gb partition (a very reasonable size) I would set up five 35Gb storage spaces and let IBM i do its thing. The extra 25Gb is a bonus since you don't need to start RAID on the guest partition.

An interesting research project would be to see if a guest partition with all 17Gb drives would out perform one with 35Gb drives, or 70Gb drives. I can bet on the outcome but it will be fun to do the test. If someone could provide a couple of data sets large enough for the test and a routine to use them, I'd be willing to work with Larry to set up a test partition (both physical and hosted) and try it.

Jim Oberholtzer
Chief Technical Architect
Agile Technology Architects


On 6/24/2011 8:48 AM, Jeff Crosby wrote:

I thought storage spaces were scatter-loaded just like everything else
on the system. Or am I wrong?


On Fri, Jun 24, 2011 at 9:08 AM, Jack Kingsley<iseriesflorida@xxxxxxxxx> wrote:

> Just to clarify this then, 1 storage space of 150GB would have 1 disk arm, 3
> of 50GB each would then possibly use 3?? I really didn't think about this
> aspect of creating storage spaces is why I ask.
>
> On Fri, Jun 24, 2011 at 8:11 AM, Jim Oberholtzer<midrangel@xxxxxxxxxx>wrote:
>

>> The reason is to provide IBM i with arms to manage. Creating one
>> storage space would be the same as giving an IBM i instance only one
>> disk drive. Bad plan from an I/O performance stand point. The
>> architecture just works better when it's allowed to do what it is
>> designed to do.
>>
>> Jim Oberholtzer
>> Chief Technical Architect
>> Agile Technology Architects
>>
>>
>> On 6/23/2011 3:19 PM, Jack Kingsley wrote:

>> > Jim, curious, I never heard of having a storage space only based on

>> 35GB??,

>> > could you elaborate on this part. If I need 150GB of space I would just
>> > create 1 storage space.
>> >
>> > On Thu, Jun 23, 2011 at 4:01 PM, Evan Harris<auctionitis@xxxxxxxxx>

>> wrote:

>> >

>> >> > Yes, the partition will be created with a HMC
>> >> >
>> >> > On Fri, Jun 24, 2011 at 12:04 AM, Jack Kingsley
>> >> > <iseriesflorida@xxxxxxxxx> wrote:

>> >>> > > Evan, are you creating this with an HMC or ??
>> >>> > >
>> >>> > > On Wed, Jun 22, 2011 at 6:21 PM, Evan Harris<

>> auctionitis@xxxxxxxxx>

>> >> > wrote:

>> >>> > >

>> >>>> > >> Hi Jim
>> >>>> > >>
>> >>>> > >> Thanks again for all the feedback. Your guess about the memory

>> may

>> >>>> > >> well be correct - I know the machine in question did not have

>> loads of

>> >>>> > >> memory at the time.
>> >>>> > >>
>> >>>> > >> --
>> >>>> > >> Regards
>> >>>> > >> Evan Harris
>> >>>> > >> http://www.auctionitis.co.nz
>> >>>> > >> --
>> >>>> > >> This is the Midrange Systems Technical Discussion (MIDRANGE-L)

-- Jeff Crosby VP Information Systems UniPro FoodService/Dilgard P.O. Box 13369 Ft. Wayne, IN 46868-3369 260-422-7531 www.dilgardfoods.com