EVA 4400: one or two disk groups?

[welldone777]

I have EVA 4400 dual controllers with 24 disks.
I plan to create one default disk group. There will be one virtual disk (2 Tb). It will be used for 8 ESX-servers. Is is right?
Or I need to create at least two disk groups?
Are there advantages of using two disk groups?

[Jozef_Novak]

Hello,

Vdisks cannot span multiple disk groups. So if you plan for one large Vdisk, your only option is to create one big default disk group.

Multiple disk groups can have benefits in database environment, where different database components can be located in multiple disk groups for better performance. However, for ESX, I am not really sure about what is the optimal configuration from storage standpoint.

J.

[Steven Clementi]

What is/are the size(s) of the 24 disks?

Will your vmware environment have exclusive access to the EVA? or will you be sharing with other physical servers and/or operating systems?

When it comes to sizing your datastores for ESX, you may want to use several smaller virtual disks vs. 1 larger disk. This will allow for flexibility for seperating out groups of servers.

How will you be backing up your ESX environment? This may make you want to think about using multiple smaller disks vs. 1 or 2 large disks.


Steven

[Uwe Zessin]

Multiple virtual disks means scattered free space, but one large datastore means that one EVA controller is not really used.

And it can become a bottleneck if you are making extensive use of meta-data changes (start/stop VM, use snapshots, many deployments), because they require SCSI reservations.

I don't see much advantage of using two disk groups with only 24 disk drives. Remember that usually the capacity of two disk drives is reserved for a 'virtualized spare disk'. This so-called 'protection level' is configured per-disk group!

Let us assume you use 24x 300 GByte disk drives. With two disk groups you are using 2x 2x 300GB = 1.2 TeraByte just for the analog of a 'spare disk'.

[welldone777]

[b]Steven Clementi[/b]
The size of every disks is 146 Gb.
What does mean "exclusive access"? It will be sharing with 8 ESX-servers, may be it will be used by OS on physical servers.
I plan to backup ESX environment to external NAS.

[b]Uwe Zessin[/b]
I plan to add an enclosure with 12 disks in the future. Can i add they in existent disk group?

About protection level.
There are two options of requested level: Single and Double. Single is default. Is it right?
I make raid5-Vdisk. So i get one failure disk. Why i need protection level? Is it another (second) failure disk?

About zoning. I use the next:
zone1: Server1HBA1 + EVAController1Port1
zone2: Server1HBA1 + EVAController2Port1
zone3: Server1HBA2 + EVAController1Port2
zone4: Server1HBA2 + EVAController2Port2

What is your advice? May be the next?
zone1: Server1HBA1 + EVAController1Port1+EVAController2Port1
zone2: Server1HBA2 + EVAController1Port2+EVAController2Port2

Or next?

zone1: Server1HBA1 + EVAController1Port1+EVAController1Port2
zone2: Server1HBA1 + EVAController2Port1+EVAController2Port2
zone3: Server1HBA2 + EVAController1Port1+EVAController1Port2
zone4: Server1HBA2 + EVAController2Port1+EVAController2Port2

[Uwe Zessin]

By exclusive access, I guess, he meant that no other servers with other operating systems have access to the EVA.

There is no problem to add another disk drive enclosure and add its disk drives to an existing disk group.

Single protection level is default, yes.
Now, "protection level" is simply A STUPID NAME BECAUSE IT DOES NOT PROTECT YOUR DATA !!

If you create a virtual disk in VRAID-0 and lose a physical disk drive - you have lost data -- no matter if it is set to 'none', 'single' or even 'double'.

As I have written above, think of it as a 'virtualization of spare disks'. A spare disk does not protect data in a traditional RAID array either.


We can discuss the internal disk group organisation, but in the *worst case*, the EVA can tolerate on disk failure at a time with VRAID-5. A protection level of single/double makes sure that there is enough capacity left to allow the EVA to rebuild VRAID-1/5(/6) redundancy.


About the zoning...
will this be one fabric ? I suggest to use two switches at least which are not interconnected. Put all server's HBA1 and controller's Port_1 to the first switch and the other ports to one switch.
Then zone from one HBA to both controller ports.

[welldone777]

So one disk (single level) is enough to make redundancy for 2 TB VRAID5 on 24 disks? How many disks are needed for double level?

I use 2 switches with interconnect. One fabric (a guess :) ). The first - principal role, the second - Subordinate role.
Please see attached file.

[Sheldon Smith · Accepted solution]

For the zoning, recommended would be
zone1: Server1HBA1 + EVAController1Port1+EVAController2Port1
zone2: Server1HBA2 + EVAController1Port2+EVAController2Port2
with two isolated fabrics (switches), one zone per fabric, or in your case, one zone per switch:
Fabric 1: zone1: Server1HBA1 + EVAController1Port1+EVAController2Port1
Fabric 2: zone2: Server1HBA2 + EVAController1Port2+EVAController2Port2

There is a technical  paper on "Best practices for deploying VMware ESX Server 2.5.x with HP StorageWorks MSA, EVA, and XP arrays" http://h71019.www7.hp.com/ActiveAnswers/downloads/BestPractice_VMwareESX25_MSA-EVA-XP_1105.pdf and another on "VMware Infrastructure 3, HP StorageWorks best practices" http://h71019.www7.hp.com/ActiveAnswers/downloads/VMware3_StorageWorks_BestPractice.pdf

[Uwe Zessin]

Protection level 'single' reserves the capacity of two(2) disk drives and 'double' reserves four(4).
The reason is how the EVA implements VRAID-1.

Again: The 'protection level' does not 'make redundancy' - the redundancy is part of the VRAID-1/5(/6) organiation of a virtual disk.

[welldone777]

Vmware StorageWorks BestPractise is very useful, thank you.
I can't see any advantages of using zoning else security control.
There two isolated fabrics (switches) are recommended. Are there advantages of isolated fabrics?
For example i have 2 fabrics (2 switches) with 20 zones for each. I need to configure 2 Brocade switches. If i use one fabric (two switches with interlinks) - 40 zones, i need to configure one brocade switch (second one has subordinate role.