3PAR Users Group

A Storage Administrator Community




Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: New Virtual Volume Max size frustration
PostPosted: Mon Feb 04, 2019 11:49 am 

Joined: Mon Feb 04, 2019 11:44 am
Posts: 2
I recently added 24 1.2TB FC Drives with an enclosure.
I want to create a virtual volume using all the space.

The CPG says Estimated maximum CPG size
19,248 GiB

My question is what is the largest I should create the virtual volume ?

HPE Claimed I can get 21.5 TB usable space. Do I need to leave 10% free when I create the virtual volume? When I initially created it I got warnings saying it was at 100% used space.

Thanks.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Virtual Volume Max size frustration
PostPosted: Tue Feb 05, 2019 12:29 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 764
Location: Europe
With 3PAR OS 3.3.1 you can create thin volumes up to 64 TB, with dedupe and/or compression or earlier versions of 3PAR OS, the max is 16TB.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Virtual Volume Max size frustration
PostPosted: Tue Feb 05, 2019 3:39 pm 

Joined: Mon Feb 04, 2019 11:44 am
Posts: 2
I understand what the Max limits are. That wasn't the question.

The question was If I create a virtual volume 100% of the available space I get critical warnings.

My question was is it best practice to create a virtual volume no more then 90% of the available space?


Top
 Profile  
Reply with quote  
 Post subject: Re: New Virtual Volume Max size frustration
PostPosted: Tue Feb 05, 2019 4:21 pm 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 764
Location: Europe
Well, that is a question which raises more.

Will you use replication? (If so there will be snapshots)
Do you plan to use snapshots in general?(multiple external applications can/may/will use snapshots)
What type of volumes will you use?
What sparring level are you using and what is the hardware config?(nodes, cages,drives)
How many drives can you accept failing before replacing and rebuilding? (naturally simulatious failures are decided by RAID level)

Answer «correct» on all of these and you can safely use ~100%, answer «wrong» and it could be way less. The only Best Practice (which is the general advise for the general use case) is always ensure you add more drives before you go full.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Virtual Volume Max size frustration
PostPosted: Wed Feb 06, 2019 8:20 am 

Joined: Tue Sep 11, 2012 1:58 am
Posts: 14
Location: Mechelen, Belgium
I'm also curious why you would want to create such a huge LUN. It implies having a single disk queue, which can quickly result in degraded performance, both ingress & egress. Especially on spinning media.

Depending on the use case I would consider splitting the CPG in 'acceptable' LUN sizes and trust your multipathing to properly handle your queues.


Top
 Profile  
Reply with quote  
 Post subject: Re: New Virtual Volume Max size frustration
PostPosted: Tue Feb 12, 2019 10:25 pm 
Site Admin
User avatar

Joined: Tue Aug 18, 2009 10:35 pm
Posts: 1207
Location: Dallas, Texas
Assuming your not doing thin provisioning, dedupe/compress, and therefore won't run out of space... 3PAR can fully provision 100% of the usable space without taking a performance hit like some modern arrays, software defined storage clusters, that need 10% - 20% free space to run optimal.

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


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 


Who is online

Users browsing this forum: Google [Bot] and 11 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group | DVGFX2 by: Matt