Help Me Decide: DAS (Shared) Storage or iSCSI Storage? (MD3000/MD3000i)

[s1xth]

For the last month I have been doing tons of research trying to decide what kind of storage setup I should purchase for my next VM implementation. I know the PRO's and CON's of both solutions, just having a tough time making a decision! I am hoping someone could share some experiences with the same kind of services/servers/environment and give me an idea on what would be the best solution for me.

I have a smaller budget for the quarter, $20,000. I will be buying two Dell R710 servers along with either one of above, a MD3000 or MD3000i, if its the iSCSI I will also need a gig switch for connectivity. The MD3000 now supports shared LUN's for vsphere/clustering/ha etc. I already priced this out and it fits in my budget.

I will be virtualizing a core backend SQL server(currently physical with a dual quad proc WAY OVER kill sits at 10% MAX cpu all day long) (not super heavy hit, I would mid range, about 500 transactions/s at full bore), along with a core front-end web server(currently a VM with 4vCPU), along with a few other low end file servers. Depending on performance there may also be an Exchange front end server along with a public folder server down the line.

I am trying to decide if I should go iSCSI or DAS. My goal of course is to have HA on all servers, so alll will be in a cluster. There should be enough resources available for that kind of configuration, I hope.

Thoughts?

[AndreTheGiant]

If you plan to have only 2 nodes, than also MD3000 could be a good choice.

But MD3000i (or other similar entry level iSCSI solution) are more scalable, so be sure to what you need.

Also the VMware license type could be important: do you play to use Essential/Essential Plus (is this case the bundle include 6 processor)?

And which of backup will you use? With iSCSI you can do a SAN backup.

Andre

[alex555550]

ISCSI. Because you can easly conenct additional Servers. And you can use VCB in an VM.

Tell your`re dell sales rep you also get an IBM offer, with an DS4700 Exoress, an he will lower his price. Connect the ISCSI to a seperate Network, to get max perofrmance. Think about SATA Drives because of their Space!

Nachricht geändert durch alex555550

[s1xth]

Guys-

Thanks for the advice. I have been so unsure about iSCSI because of performance. I am virtualizing a core sql server and possibly two small Exchange servers (front end and public folders). From what I have read these should have no problem running over iSCSI. (i am hoping) I know with ESXi 4.0 you can use MPIO and use two links for 2GB throughput, the MD3000i can handle that correct?

As far as my configuration goes, I going to configure the iSCSI network to be completely separate from my internal network, I am just going to have two Dell 5424 24 port switches standalone for direct connection to the iSCSI box. I definitly think going iSCSi is going to be the best bet, because when I want to add more servers to my cluster (HA) I can, as with the DAS solution I will only be able to add two more for a total of four servers. There is no way I will be able to use 3.5TB of data between four boxes, I just get worried about the throughput and performance when you add more servers to the iSCSI box.

Its interesting you mention tha IBM boxt, I just got a quote from my Dell rep for two R710s and an MD3000i and two switches and I couldnt believe the price of the 3000i, about two months ago I priced it out and it was $3000 cheaper!! I am going to say that I have another quote on another box and see what they can do, thanks for the advice.

As far as the SATA drives are concerned, the Dell rep told me to stick with the 300GB 15ks, what are your thoughts on that? I originally configured the box with 400GB 10ks, but he told me no after I said I will have a sql box on it, (again its a core sql box and does about 500-700 transactions seconds. Which isnt much for the main sql box, its a dual quad box with 6 15k drives and it sits at 10% CPU all day long, I know SQL is all disk and io though thats what made me concerned about iSCSi.

[AndreTheGiant]

I know with ESXi 4.0 you can use MPIO and use two links for 2GB throughput, the MD3000i can handle that correct?

ESX(i) 4 has a new iSCSI initiator and support Jumbo Frame in production, so it could be a good choice.

MPIO on MD3000i is the same that on ESX 3.5: you can use different path for different LUN (good choice for MD3000i), create at least 2 "LUN", assign on different storage processor and you have a good configuration.

Andre

[TimPhillips]

I`ve used esx but for now I decided to migrate to 3d party offer beause of need such useful stuff as RAID and Thin Provisioning, and decided to use Starwind, it`s shown very stable.

[AndreTheGiant]

In ESX 4 you can use thin provisioning (for vmdk file) from GUI.

Andre

[TimPhillips]

Wow! Thanks! That`s cool. But we already deployed Starwind and prefer using it.

[AndreTheGiant]

No problem.

Remember that thin provisioning at storage level and at vmdk level are different, and you can combine them togehter.

Andre

[s1xth]

Andre- I am planning on staying with my current backup scheme, using Acronis inside the VM. It has been working well, maybe down the line I will start looking into VCB and other oferings for SAN backup. I will have to do more research into that area.

Thanks!!

[glynnd1]

s1xth, unless you know that you are never going to grow beyond two ESX hosts then you need to strongly consider iSCSI, David.

[TimPhillips]

Andre, and what the difference? Basically this functions has one goal and must use one way of implementing.

And I can`t say that that iSCSI limited to two or three esx hosts. For now we use 4 hosts and about ten virtual machines, every is fine.

[s1xth]

I have decided to go with iSCSI, hopefully it will be able to handle the speed and performance that I need without 10Gig ethernet. I am planning on connecting three hosts and using MPIO along with jumbo frames.

[Formatter]

So can anyone tell me why not to use direct attached storage? Performance would be greatly improved. Also ESXI will use anything ESX will wont it?

[DSTAVERT]

Performance is only one small part of virtualization. You loose so much flexibility if you don't have shared storage. Everything about ESX(i) depends on shared storage. HA, vmotion, etc.

[Formatter]

So with a HP StorageWorks Modular Smart Array 2312sa G2 Dual Controller that would be direct attached would not be a good idea?

[DSTAVERT]

Yes that works but the arguments for that aren't any different than the very first post about the MD3000. Limited expansion.

[s1xth]

Definitly go iSCSI. I am just waiting for Dell to fix the MD3000i MPIO and Jumbo Frames problems and I will hopefully be picking one up soon, and slowly moving some VM's from local storage to the san via storage vmotion. :smileyhappy: Really looking forward to moving to another level, I am DONE with local storage.

[Brechreiz]

@[~511210]:

Can you describe, which Problem you mean with " MD3000i MPIO und Jumbo Frames"? I have a Setup 2 R610, PC 5424 Switch und MD3000i SAN with ESX 4.0. Have so far not seen any Problems with Jumbo and MPIO. (enable Round Robin)

[s1xth]

@[~648179] Thats awesome to hear you havent had any issues. I will keep your name in the back of my head when I get my unit. The reason I said there are issues is because there have been many posts on the forums here stating that when people enable jumbo frames they have problems, or the performance is worse. I believe there is a thread in the storage forum dedicated to md3000i. There are though, alot of people that have not had any problems. When I was at VMworld I was talking to a couple Dell engineers and they relayed to me that they are aware of the problems and performance issues with jumbo frames and MPIO and told me to hold off on getting one until they fix it, which should be soon. Its good to hear that you are NOT having any issues.

A couple questions on your setup, I see you went with the R610's, did you go with broadcom nics with toe and iscsi offload or did you go with Intel cards?(i know the server has four broadcoms built in, but did you get any addin cards also) Dell is telling me not go with the Broadcoms and go with the Intels, although the Intels dont have iscsi offloading (from what I saw). Finally, did you go with 146GB 15k's or 300GB 15k's? Just curious.

[Brechreiz]

@

Somewhere here @ the Community Forum i read that the ESX 4.0 utilize not fully the iscsi targets. (when there where only 3-4 VM's)

A Setting at the advanced settings should help here, but is not recommend for many VM's. ( I have not set it)

My Setup: 2x R610 with 4x Broadcom with TCP/IP/ISCSI Offload for ISCSI , 4 Port Intel VT for VM Traffic

MD3000i : 6x 146G 15K Raid-10 > 2 Targets , 5x146G Raid-5 > 2 Targets, 1 Hotspare. (right now i would buy 300/450G, ordering was in April with high price tag for the bigger ones)

So I have 4 Targets to utilize the 4 Ports from my MD3000i (best case) : Hardware/Software Setup this way:

[s1xth]

Thats going to be my exact setup, exact two raid 5, each with two targets. Exactly what I want to do. :smileyhappy:

[dntrprtr]

can yuo pls tell me @ the pros and cons of iSCSI,i'm trying t decice if i activate this system in my laptop,i have two more pcs at hme.would i become a target for hackers?

thank you

[TobiasKracht]

No, you wouldn`t become a hacker`s target. Don`t worry. If you are worried about secure of your data iSCSI targets can offer you CHAP authentification while connecting to target and IPSec connections while transferring data over the netwrok.

StarWind Software R&D