Oops - typo city.
I said:
Whether one is a Hot Spare and there are 7 active in the RAID-6 set, or you have RAID-6 with all pulling their share.
when I meant:
Whether one is a Hot Spare and there are 7 active in the RAID-5 set, or you have RAID-6 with all pulling their share.
Neil Palmer, Waterloo, Ontario, Canada
(This account not monitored for personal mail,
remove the last two letters before @ for that)
--------------------------------------------
On Tue, 10/22/13, Neil Palmer <neilpalmer400mr@xxxxxxxx> wrote:
Subject: Re: Disk requirement (performance-wise) on a Power 7 replacing a System i 520
To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx>
Received: Tuesday, October 22, 2013, 10:30 PM
Larry,
What are your thoughts on using RAID-6 instead of RAID-5
with Hot Spare ?
(Assuming disk busy % isn't that high).
I just don't like the idea of a disk sitting there doing
basically nothing when it could be providing additional
protection and another arm to spread data over.
Haven't done that with "spinny" disks, but did a new box
recently with 256GB memory and 18x387GB SSD's (all in an
EDR1 Ultra-SSD Drawer drawer and protected with
RAID-6). What a screamer !!
Anyway, for Jeff's smaller system situation, at only US$498
each you may as well fill out the CEC with 8 x 139.5GB 15k
RPM disks.
Whether one is a Hot Spare and there are 7 active in the
RAID-6 set, or you have RAID-6 with all pulling their
share.
I also like the suggestion, if disk % busy isn't too high
and 558GB of usable disk is enough, of getting better
protection by going to 8 x 139.5GB disks in a Mirrored
instead of RAID configuration.
Neil Palmer, Waterloo, Ontario, Canada
(This account not monitored for personal mail,
remove the last two letters before @ for that)
--------------------------------------------
On Tue, 10/22/13, DrFranken <midrange@xxxxxxxxxxxx>
wrote:
Subject: Re: Disk requirement (performance-wise) on a Power
7 replacing a System i 520
To: "Midrange Systems Technical Discussion" <midrange-l@xxxxxxxxxxxx>
Received: Tuesday, October 22, 2013, 1:17 PM
Add to Roberto's comments that the
36G drives came in 10K RPM and 15K
RPM flavors. You probably have 15K Units (FC #4326) but
not
for sure.
Remember that too few drives can really cripple your
performance,
despite vastly more CPW if you can't get to the data
you're
hosed!
Also remember the price of drives now is fabulously lower
than those
older drives when they were new! So I always recommend
that
you start
with 8 drives in a RAID 5 with hot spare configuration.
One 'simple' thing to do is on your system do WRKDSKSTS.
Wait 5 minutes
and do F5. Then look at the % Busy column (far right.)
Tell
us what
those numbers are. DO do this when the system is at it's
busiest time so
you get numbers that are reasonable.
If what you see is 40 and 50% or higher (not likely) then
8
arms will
never be enough. If you're seeing 1s and 2s though then 8
will be fine.
One more thing. MEMORY. It's cheaper than ever, get a lot.
It helps disk
business a lot!
- Larry "DrFranken"
Bolhuis
www.frankeni.com
www.iDevCloud.com
www.iInTheCloud.com
On 10/22/2013 1:08 PM, Roberto José Etcheverry Romero
wrote:
> 16drives on a 520 means you have at least one 0595
and
drives on both
> the CEC (with it's sucky 40mb controller) and the
0595
(with a wide
> range of controllers).
> I would think that any controller at the p7 level
would
stomp the
> ground with those. I'm not so sure on the disk arm
side, i keep
> reading that a bare min would be 6 arms...
> To be able to compare properly you would need to get
a
rack config, or
> at least list the disk controllers and which drives
are
hooked up to
> which controller.
> And check which controller would be on the power7
machine...
>
> Best Regards,
>
>
> On Tue, Oct 22, 2013 at 2:00 PM, Jeff Crosby <jlcrosby@xxxxxxxxxxxxxxxx>
wrote:
>> All,
>>
>> I've asked a BP for a quote on a Power 7 to
replace
our System i 520,
>> thinking that maybe the 3 year cost wouldn't be
much more than the
>> maintenance alone on the System i. Haven't
received the quote yet, so I
>> don't know if I'm delusional or not.
>>
>> Anyway, the System i has 16 ~36gb drives at only
20% capacity. IOW we only
>> have 98gb data on the System i. Isn't the
smallest drive available on the
>> Power 7 larger than that? At a minimum I
would want 4 drives, raided, with
>> a 5th as a hot spare. Any way to tell the
performance, disk-wise, of that
>> system as compared to our current system?
>>
>> Thanks.
>>
>> --
>> Jeff Crosby
>> VP Information Systems
>> UniPro FoodService/Dilgard
>> P.O. Box 13369
>> Ft. Wayne, IN 46868-3369
>> 260-422-7531
>> www.dilgardfoods.com
>>
--
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