Vmware Software RAID

[marvinicius]

I work with HP Proliant DL380 G6 servers, with P410i Contoller, 32 GB ram memory and 4 HD´s with 146 GB, that are connect to Hitachi Data System - Adaptable Modular Storage 2500. I am going to install two hosts with VMware ESX version 4.0.0 and a virtual center with VMware vCenter Server 4.0 and i am going to connect this hosts to hitachi data system. I want to create four LUN´s with 512 GB and join them using software RAID and make it be mananged by Vcenter Server. I would like to know:

1. If it is possible?

2. If there is any version of VMware that can deal with it?

3. How can i do it?

4. Is going to improve the Vmware performance or degrade it?

Thanks

Marvinicius

[MattG]

What is your goal? A 2 TB LUN? If so, why not just create a 2 TB Raid Group.

vCenter does not get assigned LUNS, you assign them to all of the hosts. So if you create 4 500GB LUNs, you would assign them to all of the hosts that will share the data.

I would think MS OS raid config would work if you really wanted to do that, but my question is why?

-Matt

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[a_p_]

You could join the 4 LUNs to one 2TB datastore (which is kind of a RAID 0), however as Matt already mentioned, this does not make any sense.

In an environment like yours protection should be configured on the storage side.

André

[marvinicius]

Matt and Andre,

Thank you very much for your answer. According to Hitachi Data System seller this storage (AMS 2500) have a better performance working with 512 GB size LUN´s e recomended us to group LUN´s with VMware managing the LUN´s and despite being 2 TB = 4 x 512 GB he says that vmware storage would be seen as one big disk. Anyway, this recomendation seeks performance.

Talking to a friend he said that the vmware performance will be degraded and he didin´t recomend it because he didn´t know how data will be recorded, in one LUN and when it is full start another LUN or spread data between LUN´s. I would like to know if this is true.

Marvinicius

[MattG]

Performance really comes down to IOPS and IOPS are best served with more spindles. So if you could have a LUN with 10 spindles it will have better performance than one with 5 spindles.

If you go with SSDs you can get crazy IOPS on a single "spindle"

-MattG

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[marvinicius]

Sorry,

but i didn´t understand the concept of spindles.

[MattG]

Spindles are another name for Hard Disks. 5 Hard disks = 5 spindles.

-MattG

[MrJambi]

Keep in mind that if you've got four 512 GB disks, any RAID protection scheme besides simple striping (which isn't a protection scheme anyway) means you'll get less than a 2 TB LUN. With 4 drives, RAID 1 gives you just 1 TB while RAID 5 (one parity drive) would give you 1.5 TB. This is generic RAID, nothing to do with VMware per se.

[RParker]

any RAID protection scheme besides simple striping (which isn't a protection scheme anyway)

All very good points.

[RParker]

Is going to improve the Vmware performance or degrade it?

Think software. RAID is done at the hardware level, you should choose hardware RAID instead of a software RAID. Software means controlled by an OS, you don't want your OS further bogged down by a file system overhead. Especially when the OS is already in a VM.

In short, this will degrade performance, and it's just not a good idea. Make the RAID hardware.

[Josh26]

Hi,

Discussions about performance aside, vmware does not support any form of software RAID, from vcenter or otherwise.

[marvinicius]

Thank you very much Rparker, Matt and Josh for your help. I would like to ask one more thing what about LVM?

Abs,

Marvinicius

[DSTAVERT]

You need to be more specific with your question. VMware ESX does not directly support any file system other than it's own VMKFS file system. VMware ESX supports other file systems indirectly through an attached NFS datastore. Virtual machines can support whatever file system they have available. A Linux Virtual Machine can support LVM.

[marvinicius]

I would like to create virtual server installed with Windows Server 2003 and put them inside a HDS external Storage, but we are thinking about a way to prepare storage area. Somebody told me about LVM and said that we could configure storage area this way.

abs

marvinicius

[DSTAVERT]

You should really look for some professional onsite guidance. Perhaps your storage vendor can provide setup help or suggest someone. If you don't choose professional assistance I would suggest you set up the different possibilities and test to find the most suitable for your situation.

[Josh26]

Hi,

I'm not familiar with the storage you're referring to - if you want advise on that you'll have to be telling us what kind of technology it is.

But regardless of the storage, ESX supports one file system - its own. You cannot use software RAID, via LVM or any other technology, from within ESX. You can make mirrors within the guest, but if that's what you're calling "RAID", you're doing something wrong.