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 Post subject: RAID 6 - LFF - Not enough free disk space?
PostPosted: Wed Nov 13, 2013 7:45 pm 

Joined: Wed Nov 13, 2013 7:39 pm
Posts: 1
Hello,

We have a new 3PAR 7200 with an additional Large Form Factor drive chassis. There are (8) 3TB 7200K Near Line LFF drives in the LFF chassis. There are no SFF drives. The system will not let us create a RAID 6, claiming there is not enough available free space? Why would this be?

Is it also true that we can't create a RAID 5 with NL drives? When we try and create a RAID 5 across the NL drives, it states the drive configuration is not supported?


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 Post subject: Re: RAID 6 - LFF - Not enough free disk space?
PostPosted: Wed Nov 13, 2013 11:56 pm 

Joined: Thu Oct 24, 2013 6:50 pm
Posts: 185
Check your availability level. It defaults to "cage", and you probably don't have enough cages to do RAID 6. Changing to "mag" should resolve it.


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 Post subject: Re: RAID 6 - LFF - Not enough free disk space?
PostPosted: Thu Nov 14, 2013 3:12 am 

Joined: Tue May 28, 2013 6:32 am
Posts: 20
Hi
change availability from cage to magazine also there are hardware restrictions on raid configuration
as for raid 5 it's disabled by default for NL drives but it is a system parameter
in CLI write "setsys AllowR5OnNLDrives yes"
Regards


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 Post subject: Re: RAID 6 - LFF - Not enough free disk space?
PostPosted: Thu Nov 14, 2013 6:38 am 

Joined: Sun Jul 29, 2012 9:30 am
Posts: 576
I did not realize the concept of "Magazine" existed in the 7000 series as the drives all plug into the back-plane and the desired HA would be cage if you have enough trays to allow for a tray failure.


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 Post subject: Re: RAID 6 - LFF - Not enough free disk space?
PostPosted: Thu Nov 14, 2013 3:41 pm 

Joined: Wed May 15, 2013 7:07 am
Posts: 15
Hi.

The 3PAR 7200 has 2 controllers.
Each of them handles half of the disks during normal operation (the other can take over).

So - each controller is managing 4 disks out of 8, therefor you cannot create RAID6 in such configuration (which actually means RAID60) .

I was hit by similar problem, as I have a 7200 with 12 NL disks in the second cage,
which means 6 NL disks per controller.
I can create RAID 6 , however I am limited to 4+2 set size which means 33% disk space penalty,
and I cannot use something reasonable like 6+2 or 8+2 set size.
So I opted to not use RAID6 at all on those disks.

Your options are:

* Create RAID1 (RAID10) volumes for production data.

* Create RAID5 (RAID50) CPG and volumes only for non production data, such as snapshots,
backup or archives files.
For this you need to enable "AllowR5OnNLDrives" as mentioned by giladzzz above.

* Or - purchase more NL disks.

Yizhar


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 Post subject: Re: RAID 6 - LFF - Not enough free disk space?
PostPosted: Thu Nov 14, 2013 5:17 pm 

Joined: Thu Oct 24, 2013 6:50 pm
Posts: 185
kluken wrote:
I did not realize the concept of "Magazine" existed in the 7000 series as the drives all plug into the back-plane and the desired HA would be cage if you have enough trays to allow for a tray failure.


Someone who doesn't have enough trays to do "cage", I can tell you I've configured our 7200 with "magazine". Because it doesn't actually have magazines, it's effectively just a case of a GUI using standardised terminology across the 3PAR range, and in this case it can be thought of as single disk magazines.


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 Post subject: Re: RAID 6 - LFF - Not enough free disk space?
PostPosted: Fri Nov 15, 2013 1:27 pm 
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Joined: Tue Aug 18, 2009 10:35 pm
Posts: 1328
Location: Dallas, Texas
Its a vocabulary problem... technically, a hot plug drive is a magazine of 1. ;)

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Richard Siemers
The views and opinions expressed are my own and do not necessarily reflect those of my employer.


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