Raid on SAN with ESXi

[GeekGuy123]

I'm confused on how Raid would work with a remote SAN.

I understand that ESX uses the card on the server.  The HD's on the server are configured as a raid array.  But how do you configure the SAN as an array?

Also I saw a post on another forum that stated you should not use Raid 5 for VMWare.  Any opinions?

[a_p_]

Welcome to the Community,

a storage system also uses a RAID controller (like your ESXi host). You will have to configure the RAID on the storage system and create LUNs which you then present to the ESXi host. Depending on your setup you may use an iSCSI or FC connection to connect to the storage system over your SAN.

André

[weinstein5]

Welcome to the Community -  RAID is nothing more than how you string multiple disks together to increase the amount of accessible storage, provide certain perfromance characteristics and to provide fault tolerance - You configure SAN storage the same way you configure internal storage in a server - you have a set a of disks and use the management and decide what RAID level you will set -

There is no problems in using RAID 5 with VMware - you really configure you RAID sets based on the type of disk performance you are looking to provide to you VMs hosted on your ESXi server

[Josh26]

Think of the SAN as another computer. You configure the RAID on the SAN - on the SAN, not on any of your servers.

I highly recommend RAID5 for many purposes.

[GeekGuy123]

David,

Thanks for the reply.

I guess what’s confusing me is how you can have two different servers pointing to the same set of disks on a SAN each using a different raid card to do one raid set.

I understand your point of having one server with one raid card managing 3 disks on the SAN. But I saw a demo where you had two ESX boxes using the same Virtual files off a SAN.

Not quite got this concept wrapped around my beady brain.

Dave

[kjb007]

I think you misunderstand how the RAID cards in a server work as opposed to RAID in a SAN.  RAID cards manage disks that are directly connected to those cards.  In a server, there is typically a SCSI/SAS connection from the controller/adapter to the disks themselves.

RAID cards in your server do not connect to a SAN.  A SAN is connected to either using FC (fiber channel HBA's) or over IP for network based storage.  A direct attached disk array can connect using scsi, but that is no longer a san per se, it is more or less an extension of your local server and allows it to manage a greater number of disks that are directly attached to that controller's bus.

-KjB

[GeekGuy123]

Sorry if I'm being dense.  But my Dell dude said that the SAN doesn't have a RAID card, and you use the card off the server.  But you  say not.

Does the SAN have the ability to do RAID on it's own?  Without a card?  If so then that would ease my confusion.

Dave

[weinstein5]

From what you are saying the 'Dell Dude' is NOTselling you a SAN but an external storage array -

A SAN - Strorage Area Network  - utlizes a network to connect your servers to the storage device. The network can be either FIber Channel (FC) or IP based for iSCSI. The Storage Device handles the RAID configuration and manages the shared access,

An External Storage array connects directly to server  through the SCSI/RAID card and you would configure the RAID set through the server. Sharinge the RAID sets in this configuration is much more difficult than it is in a SAN

[kjb007]

Ah, you are speaking specifically of a certain product, which may have additional.  Which specific product are you referring to?

-KjB

[GeekGuy123]

Not sure what confusion there was with the Dell Dude.  I thought I was clearly speaking SAN, but wouldn't swear to what may have puked out of my mouth.

I'm looking at the Dell Powervault iSCSI SAN.  My confusion continued when the specs said it had support for RAID levels 0,1,10,5,6.  And the PERC H800 server compatibility matrix........

So once again just to be crystal clear.  The SAN has the RAID ability built in.......YES?????

[weinstein5 · Accepted solution]

The answer is YES - the Powervault witll have a PERC array card that will allow you to configure your array - you will communicate to the Powervault via iSCSI protocol across an IP network -