HPE Storage Users Group

A Storage Administrator Community




Post new topic Reply to topic  [ 3 posts ] 
Author Message
 Post subject: Adding more disk to my system
PostPosted: Tue Mar 20, 2018 10:10 am 

Joined: Tue Mar 20, 2018 10:03 am
Posts: 3
Hi Folks!

i have a doubt, right now i have a 3par 7450 with 24 SSD

8 disk 1.92TB
16 disk 480GB

We are using a CPG Raid 5 (3+1), and now are are looking for adding new disk, so here is my doubt.

I want to buy 6 disk of 1.92TB, but the HPE seller is telling me that is a bad practice, i should buy 8 disk of 1.92tb regarding to the Raid configured in the CPG, i asked why, because the raid is performed with chunklets, not the entire disk as legacy systems but i have no answer.

I was wondering if you guys can help me with disk, those disk are very expensive.

Best Regards!


Top
 Profile  
Reply with quote  
 Post subject: Re: Adding more disk to my system
PostPosted: Tue Mar 20, 2018 10:58 am 

Joined: Wed Nov 09, 2011 12:01 pm
Posts: 392
From the quickspec docs
Quote:
Minimum upgrade quantity is 4 drives per node pair or 2 drives per enclosure,
whichever is larger.


So on a 4 node system, if you don't have any expansion shelves, it'll be 4 drives x 2 node pairs = 8 drives.

Beyond that you always have to add drives in pairs to each shelf so I guess you could do 8, 12, 16 etc. drives in one upgrade.

It is the drawback of larger drives, upgrading less often but more expensive purchase (it is cheaper/GB though).


Top
 Profile  
Reply with quote  
 Post subject: Re: Adding more disk to my system
PostPosted: Wed Mar 21, 2018 2:18 am 

Joined: Mon Sep 21, 2015 2:11 pm
Posts: 1570
Location: Europe
seeeking wrote:
Hi Folks!

i have a doubt, right now i have a 3par 7450 with 24 SSD

8 disk 1.92TB
16 disk 480GB

We are using a CPG Raid 5 (3+1), and now are are looking for adding new disk, so here is my doubt.

I want to buy 6 disk of 1.92TB, but the HPE seller is telling me that is a bad practice, i should buy 8 disk of 1.92tb regarding to the Raid configured in the CPG, i asked why, because the raid is performed with chunklets, not the entire disk as legacy systems but i have no answer.

I was wondering if you guys can help me with disk, those disk are very expensive.

Best Regards!


The quick and dirty answer.. With 16 disks you can write 4 full stripes, while with 14 you only get to write 3 because the two last drives in the final stripe is busy writing one of the other 3 stripes. So it is only a performance related best practice.

_________________
The views and opinions expressed are my own and do not necessarily reflect those of my current or previous employers.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 3 posts ] 


Who is online

Users browsing this forum: Google [Bot] and 22 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