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Difference between VA and EVA

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Vipul_2
Advisor

Difference between VA and EVA

Hi Guys ,

Other than RAID levels and max storage capacity .. whats the major difference between ..say VA7xxx and EVA series(Say EVA3000) of products?

both are end-to-end Fibre

Regards ,
Vipul Bhadra
9 REPLIES
Slawomir Gora
Honored Contributor

Re: Difference between VA and EVA

Hi,

1. In VA74xx you have one (VA7110) or two (7410) redundancy group and one raid level for all of them - EVA has disk groups which can have different raid level-s
2. EVA has Continuous Access
3. EVA has Snapshots and Snapclones

etc...

Uwe Zessin
Honored Contributor

Re: Difference between VA and EVA

No, sorry. A disk group on the EVA does not have a VRAID level associated with it. VRAID is a characteristic of an individual virtual disk, which is the container for the user's data. You can have multiple virtual disks with different VRAID levels in the same disk group.
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Steven Clementi
Honored Contributor

Re: Difference between VA and EVA

But the EVA has RSS athe the Disk Group level, which is sort of like RAID5 protection in theory, but not exactly the same.

Not sure if the VA has RSS.


Steven
Steven Clementi
HP Master ASE, Storage and Clustering
MCSE (NT 4.0, W2K, W2K3)
VCP (ESX2, Vi3, vSphere4, vSphere5)
RHCE
NPP3 (Nutanix Platform Professional)
Vipul_2
Advisor

Re: Difference between VA and EVA

Sorry .. but i could not understand what was being said. From what was said i assume the difference is that EVA has virtual raid.

IBM fastt groups disks in arrays out of which virtual disks are made out (Each array has one raid level .. say RAID 1,0 or 5 ).. and then logical disks are created in this array. Each of this logical disk can be assigned to a controller.

Do both VA and EVA operate similarly?

Are there any document(Other than quickspecs..say userguide) which will simplify things for me?

Thanks for the help.

Regards,
Vip
Uwe Zessin
Honored Contributor
Solution

Re: Difference between VA and EVA

Steven:
No, I don't think so. A RSS is used to limit a failure domain. VRAID-5 stripes (4D+P) never span two RSS I have been told. So if you have two RSS, you can withstand one disk failure per RSS = 2 disk failures per disk group.

It's been too long that I looked at the inner workings of the VA to remember if it has something like RSS. By default the VA uses striped mirrors, but it can be switched to AUTORAID mode. In that case the array decides what data to store as RAID5DP (DP = double protection, so it can tolerate the failure of two disks).


Vipul:
The EVA and the VA do not work like the IBM. From the description it sounds like you create a disk array and this one is initialized with a RAID-level. Then you partition this container into multiple logical disks.

On the EVA you bind multiple disks together to form a disk group. This is a storage pool out of which you can draw capacity for your virtual disks. I have already written above that you can have different virtual disks with different VRIAD levels in the same disk group.
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Steven Clementi
Honored Contributor

Re: Difference between VA and EVA

"A RSS is used to limit a failure domain. VRAID-5 stripes (4D+P) never span two RSS I have been told. So if you have two RSS, you can withstand one disk failure per RSS = 2 disk failures per disk group."

That is exactly how I understood the technology to work, except that I did not go into detail.

Steven
Steven Clementi
HP Master ASE, Storage and Clustering
MCSE (NT 4.0, W2K, W2K3)
VCP (ESX2, Vi3, vSphere4, vSphere5)
RHCE
NPP3 (Nutanix Platform Professional)
Uwe Zessin
Honored Contributor

Re: Difference between VA and EVA

Hello Steven,

my apologies, but that is not what I had read from your description. You wrote that RSS 'is sort of like RAID5 protection in theory'.

RAID-5 is about redundancy, protecting data from a (single) disk failure.

RSS is about failure domains within one EVA disk group.
.
Steven Clementi
Honored Contributor

Re: Difference between VA and EVA

which is why I also said... "but not exactly the same."

I really need to take the time and xplain myself better. Unfortunately, I sometimes quickly answer with little time to actually post a full message.

Sorry for the confusion.

Steven
Steven Clementi
HP Master ASE, Storage and Clustering
MCSE (NT 4.0, W2K, W2K3)
VCP (ESX2, Vi3, vSphere4, vSphere5)
RHCE
NPP3 (Nutanix Platform Professional)