HPE EVA Storage

Best method for access data (scenario description inside)

 
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fjmarquez
Occasional Advisor

Best method for access data (scenario description inside)

Hi friends,

I'm thinking about the possibility of make some changes in my SAN/ESX cluster and the method of access to user related data, but I don't know very well the enterprise-level storage systems, so I need your help.

Currently, Windows user profiles and other user-related data, are accessed through a virtual machine that use 3 virtual disk located into a VMWare datastore. This datastore is a LUN inside of a FC_group of my HP EVA 4400 wich use Raid5.

I'm thinking in two options for replace this system:

1.- Attach to Virtual Machine, as RAW device, a LUN of my SAN. I think that this should improve the performance, since dissappear the virtual disks and virtual machine can access directly to RAW data.

2.- Attach to PC's and Windows Domain Controller (is a VMachine) a LUN of my SAN. I think that this method offer the best performance, since the access is direct from client machine, without virtual disk and/or virtual machines in the middle. The problem is: Is it possible? How? In the method 1, VMware virtual machines can access directly to RAW LUN, because EVA 4400 is connected directly to my Blade enclosure with FC, but the PC's are not directly connected to SAN. Maybe iSCSI is the solution?

Other questions:

a) Is it safe to access a LUN from multiple PCs concurrently?
b) hat percentage of performance improvement could be obtained with these changes?
c) Have you some recomendation?

Thank you in advance,
FJ
7 REPLIES 7
Johan Guldmyr
Honored Contributor
Solution

Re: Best method for access data (scenario description inside)

Helloes,

a) To access a LUN directly is only good if the file system supports access from several machines at the same time, and they need to be in a cluster.
fjmarquez
Occasional Advisor

Re: Best method for access data (scenario description inside)

Then, it isn't a good scenario for store user data and to allow to PC's access concurrently via iSCSI? The idea is format this LUN as NTFS and get access via iSCSI. This is my idea, but as I already said, my knowledges about enterprise-level storage systems are very poor, so probably its a bad idea...

Regards.
Johan Guldmyr
Honored Contributor

Re: Best method for access data (scenario description inside)

Why do you want to present a LUN to many servers? See this link to wikipedia, iSCSI would work, as long as you have the right file system on it:
http://en.wikipedia.org/wiki/ISCSI#Logical_Unit_Number

Why not have a file server and share the storage via samba, nfs, cifs or something like that instead?

1.-
One thing pretty easy that you could check out if you want to improve performance for your ESX servers - check out if your vdisks are spread out between the controllers and that the servers access the vdisks via the owning controller.
fjmarquez
Occasional Advisor

Re: Best method for access data (scenario description inside)

> Why do you want to present a LUN to many
> servers? See this link to wikipedia, iSCSI
> would work, as long as you have the right > file system on it:
> http://en.wikipedia.org/wiki/ISCSI#Logical_Unit_Number

> Why not have a file server and share the
> storage via samba, nfs, cifs or something > like that instead?

I don't know... is only that I though that would be better if the client accesses directly to SAN, but if you recommend me do it through a file server, I will do it.

> 1.- One thing pretty easy that you could
> check out if you want to improve
> performance for your ESX servers - check
> out if your vdisks are spread out between
> the controllers and that the servers
> access the vdisks via the owning
> controller.

Are you refering to storage adapters? Please, see the attached screenshots. I think that I only use 1 adapter (vmhba1) for all vDisk of this virtual machine.

And, what mean this?: "the servers access the vdisks via the owning controller." Do you refer to SO controller? I'm using vmware tools, so the controller is the official vmware controller. Is it right?

In any case, accepting your advices, it is say, discarding the access to LUN directly for each client and keeping active my file server, Would be better if I present the LUN to this virtual machine through RDM instead of use virtual disk, right?

Regards and thank you very much
Johan Guldmyr
Honored Contributor

Re: Best method for access data (scenario description inside)

>And, what mean this?: "the servers access the >vdisks via the owning controller." Do you >refer to SO controller? I'm using vmware >tools, so the controller is the official >vmware controller. Is it right?

I meant that on the EVA itself, (you can see this in Command View on each vdisk, it's the path/failover) each vdisk has a controller that owns it. You can see performance improvements if you spread the vdisk ownerships between the controllers.

>In any case, accepting your advices, it is >say, discarding the access to LUN directly >for each client and keeping active my file >server, Would be better if I present the LUN >to this virtual machine through RDM instead >of use virtual disk, right?

See this thread at vmware's forum for more information:

http://communities.vmware.com/message/1674662

Looks like rdm vs vmdk is more of a question about flexibility than performance.
fjmarquez
Occasional Advisor

Re: Best method for access data (scenario description inside)

> I meant that on the EVA itself, (you can see
> this in Command View on each vdisk, it's the
> path/failover) each vdisk has a controller
> that owns it. You can see performance
> improvements if you spread the vdisk
> ownerships between the controllers.

Ok, but I think that we are refering to differents things when we say "vdisk" or "virtual disk" in this conversation.

My virtual machine uses 3 VMWARE virtual disk (3 vmdk files of hundreds of GB each one). All this are inside of 1 LUN (VMFS), wich you are refering as virtual disk in Command View. Then, as Command View allow me use 1 controller per virtual disk (LUN), and all my vmware virtual disks are using same virtual disk (LUN), I'm using only 1 controller for all my vmware's virtual disk and I can't change this without change vmdk files to other vmware datastore (wich is equal to use other virtual disk (LUN)).

I've checked the controller of each virtual disk (LUN) in Command View and all my virtual disks (LUN) are using same controller, but I don't have any option for change it (see screenshot). How I can do it?

Other motive about wich I consider using an independent virtual disk (LUN) attached to vmware virtual machine (with RDM) instead of vmware virtual disk (files inside of a LUN) is for not require a virtual machine for access to this data, wich can be an advantage in some situations and for example, HP Data Protector can access directly to data for backup without need an agent installed in SO of a vmware virtual machine.

Regards
Johan Guldmyr
Honored Contributor

Re: Best method for access data (scenario description inside)

OK, I don't know what the VMWare side stuff is called.

You can change managing controller under the "preferred path/mode".

You may also have to change from the VMWare side for the vdisks/LUN you change to ctrl 2 - so that the hosts don't keep on using controller 1 (which may after a while move the vdisk/LUN back). (like preferred/fixed path)