These are actually 1.9 TB, not 1.5 Tb.
If these were the 3.72 Tb drives, would have the same opinion.
Two Raid5 parity sets, 2 hot spares, so we lose 4 drives.
With the 1.9 Tb drives, we're losing 7.9 Tb for disk protection.
With the 3.72 Tb drives, we're losing 14.88 Tb for disk protection.
Paul
-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Jim Oberholtzer
Sent: Friday, December 14, 2018 10:18 AM
To: 'Midrange Systems Technical Discussion'
Subject: RE: P9 with dual EJ14 - Raid5 and Hot Spare questions
In order to get the DASD setup you want, you will have to stop what you are
doing, end RAID and start over. Will that take significant minutes
(emphasis: significant), oh yea.
The real question to ask is: One drive is at most 1.5TB. With two hot
spares (most of my customers do, by design have two hot spares) you cut the
odds of a system failure by quite a bit if you do the math on the odds.
It's really cheap insurance.
So, are two more days of wrangling it around worth the recovery of such a
small amount of storage, part of which gets burned up by RAID striping
anyway? I highly doubt it.
It's your system, your call, but I'd consider the status quo and move on.
--
Jim Oberholtzer
Agile Technology Architects
-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxx> On Behalf Of Steinmetz,
Paul
Sent: Friday, December 14, 2018 8:43 AM
To: 'Midrange Systems Technical Discussion' <midrange-l@xxxxxxxxxxxx>
Subject: RE: P9 with dual EJ14 - Raid5 and Hot Spare questions
Internal
Paul
-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Jim
Oberholtzer
Sent: Friday, December 14, 2018 9:36 AM
To: 'Midrange Systems Technical Discussion'
Subject: RE: P9 with dual EJ14 - Raid5 and Hot Spare questions
Your second process is the correct one.
<snip>
1. Start device parity protection - RAID 5, omitting 1 disk unit.
Then
2. Start Hot Spare
</snip>
Is this a SAN or internal storage?
--
Jim Oberholtzer
Agile Technology Architects
-----Original Message-----
From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxx> On Behalf Of Steinmetz,
Paul
Sent: Friday, December 14, 2018 7:45 AM
To: 'Midrange Systems Technical Discussion' <midrange-l@xxxxxxxxxxxx>
Subject: RE: P9 with dual EJ14 - Raid5 and Hot Spare questions
Rob,
I found some verbiage from the disk management manual which states that you
need one hot spare per IOA.
But depending on how you start the hot spare, the system will create 2.
I used the option
3. Start device parity protection - RAID 5 with hot spare
What I think I needed to do is:
1. Start device parity protection - RAID 5, omitting 1 disk unit.
Then
2. Start Hot Spare
Paul
-----Original Message-----
From: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Rob
Berendt
Sent: Friday, December 14, 2018 7:46 AM
To: Midrange Systems Technical Discussion
Subject: Re: P9 with dual EJ14 - Raid5 and Hot Spare questions
A hot spare is only good for one raid group. Among your choices are:
1 - no hot spares
2 - two raid sets with one hot spare each.
3 - one raid set with one hot spare
4 - two raid sets. One with a hot spare, one without. The hot spare is not
shared between the two.
There are more options. Like two hot spares per raid set. When creating a
secondary asp, composed of SSD's being self maintained, I did this.
Rob Berendt
--
IBM Certified System Administrator - IBM i 6.1 Group Dekko Dept 1600 Mail
to: 2505 Dekko Drive
Garrett, IN 46738
Ship to: Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com
From: "Steinmetz, Paul" <PSteinmetz@xxxxxxxxxx>
To: "'Midrange Systems Technical Discussion'"
<midrange-l@xxxxxxxxxxxx>
Date: 12/13/2018 11:01 PM
Subject: P9 with dual EJ14 - Raid5 and Hot Spare questions
Sent by: "MIDRANGE-L" <midrange-l-bounces@xxxxxxxxxxxx>
When configuring disks on a new P9 with dual EJ14, 24 SSD drives Starting
parity, Raid 5 with Hot Spare, one large parity set was created.
I wanted two parity sets, parity for performance, but the option to set
parity was not available.
Is this normal behavior.
After the single set was created, additional disk options became available.
I changed parity for performance, stopped parity, then started Raid5 with
Hot spare.
Now I have two parity sets, with two Hot spares.
I really only wanted 1 Hot spare, no option for this.
I do see an option to stop Hot spare on one of the units.
I would then have to add this unit back in, but this unit would not have any
stripping, not recommended.
Any thoughts from the group?
Thank You
_____
Paul Steinmetz
IBM i Systems Administrator
Pencor Services, Inc.
462 Delaware Ave
Palmerton Pa 18071
610-826-9117 work
610-826-9188 fax
610-349-0913 cell
610-377-6012 home
psteinmetz@xxxxxxxxxx
http://www.pencor.com/
--
This is the Midrange Systems Technical Discussion (MIDRANGE-L) mailing list
To post a message email: MIDRANGE-L@xxxxxxxxxxxx To subscribe, unsubscribe,
or change list options,
visit:
https://lists.midrange.com/mailman/listinfo/midrange-l
or email: MIDRANGE-L-request@xxxxxxxxxxxx Before posting, please take a
moment to review the archives at
https://archive.midrange.com/midrange-l.
Please contact support@xxxxxxxxxxxx for any subscription related questions.
Help support midrange.com by shopping at amazon.com with our affiliate
link:
https://amazon.midrange.com
midrange.com
