Maximum number of LUNs on EVA5000

[Chuck Ciesinski]

To all,

In attempting to compare our EVA5000 to an HDS array, HDS indicates a maximum number of LUNs. Does the EVA5000 have a maximum number?

Thanks again,

Chuck Ciesinski

[Steven Clementi · Accepted solution]

Chuck:


The max amount of LUN's on an EVA 3k/5k is 512.

On the 4k/6k/8k it is 1024.

SAN Design Reference Guide, Chapter 9, Page 176.

I gon't have the link handy at the moment, only the file locally to reference it. I am sure someone will provide the link.


Steven

[Uwe Zessin]

The numbers are correct, but I'd like to point out that:

- each presented snapshot counts against that limit, too and the number of 'presentations' (a mix between presented virtual disks and fibre channel adapters) need to be calculated in large configurations, too.

- the HDS (which one?) comes from the mainframe / storage array central worlds. Such arrays are able to present _lots_ of small LUNs and have many host ports. The EVA is not positioned for those areas.

The guide that Steven has mentioned:
http://h18000.www1.hp.com/products/storageworks/san/documentation.html

[Chuck Ciesinski]

Uwe,

We are looking at the HDS-9585V (Thunder) array.

Chuck

[Peter Mattei]

Chuck

You should rather compare the HDS 9585V with the EVA8000 and you should not only look at figures.

The main difference of the two arrays is the way RAID sets are built and the ease of use.
The virtualization of the EVA allows for much easier management and automated load distribution.

On the 9585V you define multiple disk groups of up to 16 disks. Then you define a raid level and LDEV/LUN sizes per disk group.

On the EVA you create 1 to 16 disk groups (most customers use 1 or 2)
A disk group can host all drives of an EVA that is 240 on the EVA8000.
Now you can define LUNs. Each LUN can have a different size (from 1GB to 2 TB) and RAID level (0, 1, 5) and reside in the same disk group.

Looking at single LUN performance:
A LDEV on an HDS9585V resides on max 16 disks on the EVA on max 240 disks.
Gues which LUN will be faster?

Looking at capacity growth:
You can add disks to an EVA disk group and the EVA will redistribute and level existing LUNs over all disks. New LUNs will be craeted over all disks in the group. This will avoid hot spots!
In the HDS box you have to create a new disk group and create LDEVs which are only on the disk in that new disk group.

Cheers
Peter

[Chuck Ciesinski]

Peter,

I'm comparing what I have, not what I'd like to have to work with. You make some very interesting discussion points and issues that I will need to address. My biggest concern is that in my EVA, I have a mix of 72 and 146 GB drvies and in the HDS they are all 146. All are 10Krpm devices. We are going to be entering the expansion cabinet with our next disk add-on. See new question on performance monitoring..

Chuck

[Peter Mattei]

Do you have your 72 and 146GB drives in the same disk group?
Usually we put each geometry in a disk group. This is not mandatory but will guarantee equal load on each drive.

About performance. I suggest you use EVAPerf which gives you great performance figures of your array.
Go here: http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareDescription.jsp?locBasepartNum=co-30754-2〈=English

Cheers
peter

[Craig Howe_1]

We looked at the Thunder in comparison with the EVA. We Went with 2 x EVA 5000's.

As well as the virtualisation mentioned to get maximum I/Os from all the disks in a disk group, the EVA could hold the FATA (Hybrid SATA) drives in any enclosure. The Thunder needs seperate SATA enclosures for these drives only.