Solved

EVA 4400 single or double spare...

Posted on 2010-08-21
8
1,205 Views
Last Modified: 2013-11-14
When is it a bad idea to do double spare?  Does it hurt IOPS?  Does it help?

Currently I have 18 450's.  Going to add 6 more in a week.

Moved off of 146g disks (18) killed that disk group and retired disks.

I have 3 disk shelf's.

So I just wanted to get the skinny on double protection and if it was dumb.

We selected double becuase we just don't want the array to fail if we can help it.
0
Comment
Question by:smcpartlin
  • 3
  • 3
  • 2
8 Comments
 
LVL 20

Expert Comment

by:SelfGovern
Comment Utility
There is a slight performance difference for writes between RAID 5 and RAID 6; for reads there won't be anything noticeable.
0
 
LVL 1

Author Comment

by:smcpartlin
Comment Utility
On the Eva 4400 double protection is separate from the raid level.  

On our Eva 4400 raid 6 is not even selecte-able.
0
 
LVL 55

Accepted Solution

by:
andyalder earned 500 total points
Comment Utility
Single reserves 2 disks worth of data as distributed hot spares, double reserves 4 disks worth of data. It has no performance difference since the spares are distributed across all the disks a bit like a small RAID5 stripe. The spares aren't even created until needed, it's just reserved space so if you have enough room currently and set it to double you can change it to single or even none if you need that space in future. Same with the disk space reserve setting, it just stops you creating more LUNs and sets off alarms when you hit the reserve, you can always change it when you feel like it without affecting anything else.

N.B. it's not quite two or four whole disks since it doesn't have to reserve a whole disk as it takes into account the fact that it doesn't have to spare up for reserve area.
0
 
LVL 1

Author Comment

by:smcpartlin
Comment Utility
.
0
Comprehensive Backup Solutions for Microsoft

Acronis protects the complete Microsoft technology stack: Windows Server, Windows PC, laptop and Surface data; Microsoft business applications; Microsoft Hyper-V; Azure VMs; Microsoft Windows Server 2016; Microsoft Exchange 2016 and SQL Server 2016.

 
LVL 55

Expert Comment

by:andyalder
Comment Utility
Why have you posted a dot?
0
 
LVL 20

Expert Comment

by:SelfGovern
Comment Utility
Perhaps because, as I hear, "Dot's nice".
0
 
LVL 55

Expert Comment

by:andyalder
Comment Utility
0
 
LVL 1

Author Closing Comment

by:smcpartlin
Comment Utility
Thanks.
0

Featured Post

What Is Threat Intelligence?

Threat intelligence is often discussed, but rarely understood. Starting with a precise definition, along with clear business goals, is essential.

Join & Write a Comment

If you have a USB Drive that is not recognized by Windows the problem is usually that you have too many network drives or other drives that occupy all the drive letters D: E: or F: which is the normal drive letter of a usb drive. The way to correct …
We all have limited time to study long and complicated information about RAID theories, but you may be interested as to how RAID 5 works. We made it simple for you by providing the shortest and easiest explanation ever.   First we need to remind …
This tutorial will walk an individual through the process of installing the necessary services and then configuring a Windows Server 2012 system as an iSCSI target. To install the necessary roles, go to Server Manager, and select Add Roles and Featu…
This Micro Tutorial will teach you how to reformat your flash drive. Sometimes your flash drive may have issues carrying files so this will completely restore it to manufacturing settings. Make sure to backup all files before reformatting. This w…

743 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

15 Experts available now in Live!

Get 1:1 Help Now