Which storage solution is best??

[virtualbot]

Hello all,

We are planning to implement VMware in a lab environment with 15TB of storage. Most of it is SQL database. We are planning on typically about 6 to 7 ESX hosts. For such a scenario what is the best storage solution, iSCSI or Fiber? Cost is not the factor---Only performance matters.

Also can anyone please advice me about which is optimum for the above set up----7200RPM SATA or 10,000 RPM SAS disks. I am thinking on 7200RPM SATA if there isn't a big difference in performance.

TIA,

Virualbot

[philvirt]

Since cost is no issue - Fiber is the way! You will get better reliability and speed with Fiber. iSCSI works well but it does not perform like Fiber. Some new iSCSI systems will support 10g, but I still prefer Fiber.

[admin]

Well I think that an awful lot depends on your definition of optimum. You have a choice between serial attached ATA or Serial attached SCSI. SCSI tends to offer better performance and longer life of the drive than say does an ATA. Serial ATA is usually geared toward tier 2 storage where you want to keep things around but not on the fastest most expensive storage. Is there a big difference in performance, well just looking at it from a single hard drive perspective the most important factors in a Hard Drives performance are usually Seek Time and Rotational Latency. The faster the drive can seek to a sector on disk then the faster it will be able to retrieve data. SCSI Drives tend to outperform their ATA counterparts in this area.

[ejward · Accepted solution]

We're actually getting better performance on our iSCSI Equallogic SAN than our 2GB fiber EMC DMX. Not 10 or 15% better performance. I'm talking 200 to 300% better performance. EMC has beaten this to death and essentially said "Yeah, the DMX is slower". Our Clariion is also faster than the DMX. About the same performance as the Equallogic.

[virtualbot]

Thanq very much guys!!!!! so how good is the iscsi compatible with VMware because i often come across issues that mention the iscsi software initiator errors or iscsi reservations errors?

[ejward]

I guess the software initiator debate will go back and forth forever. I watched a presentation at Vmworld that showed that the software initiator is no slower than a hardware initiator. At some block sizes, it was actually faster. There is CPU overhead however, if the CPU overhead for the software initiator is going to push you over the edge, you've got bigger issues than storage. I recently migrated 280+ VMs from fiber storage to software initiator iSCSI and have noticed no degraded performance.

Third party implementers that I've dealt with say that they have not implemented a fiber solution since iSCSI became available.

On the other hand, I'm sitting in a Vmware class right now and the instructor swears by fiber. The world will come to an end if i use software initiators. He says that it comes down for contention for CPU time. My argument is that my CPU utilization id about 10%. There is no contention.

[virtualbot]

So what would be the best idea....use of a software initiator or a hardware initiator, for the iSCSI SAN?

[philvirt]

I've seen a couple of scenarios and to be real honest the best performance I've seen is still True SCSI drives transmitting through 4GB Fiber.

Regards,

Fil

[philvirt]

I've done both connecting to an DELL iSCSI SAN and noticed no difference. If you get a really good NIC with TCP OE it will not put strain on your CPU.

Regards,

Fil

[virtualbot]

Hey Fil,

Even I am a big fan of fiber, but at this point of time taking into account the minimal I/O contention and the huge variation in cost (contradicting my prev. statement "cost is not a factor"); I think iSCSI is not a bad option for this size of a set up. But then keeping in mind the future expansion plans, I am kinda skeptical about using fiber or iSCSI. I am still looking on some fiber quotes if I could get some real cheap, I might be inclined to use fiber!!!

So do you have any idea about this particlar vendor for SAN.....its COMPELLENT? Any info about how good or bad or how pricey it is??

[ejward]

I looked at Compellant when we were looking into iSCSI. It was more expensive than Equallogic but, it does iSCSI and fiber. It also has a better replication process that Equallogic. They just announced another feature that moves blocks of data that are accessed the most to the fastest sectors on each hard drive. I know of a hospital that dumped all their EMC storage for Compellent.

Look at it this way. With Compellent, you could do fiber for production, then use iSCSI with the software initiator for test / dev. You could even do a head to head comparision.

[philvirt]

I'm implementing pretty much just iSCSI now. It makes allot of sense for future growth, especially with 10g being available.

Regards,

Fil

[aguacero]

Yeah i'm looking at Compellent as a potential SAN choice for us over EqualLogic (currently inhouse). Tomorrow I'm heading over to a customer of Xiotech to see their product in live production. So far, I'm leaning towards Compellent due to performance and pricing.

fyi. I'm heading to a Compellent event at the NY Stock Exchange with partners VMWare & Riverbed on April 9th. If interested e-mail in attending nyse@compellent.com.

If you found this information useful, please consider awarding points for "Correct" or "Helpful". Thanks!!!

[virtualbot]

Hey, that's interesting to know that compellent is in the race with major vendors. I am planning to get some quotes from compellent before I decide on it. and is the variation in the price huge when compared to Equallogic????????

[ejward]

One word of caution on Xiotech. If you speak to one of their sales people. Even if it's just in passing. You will get phone calls and emails for the rest of your life. I spoke to someone at Xiotech at a conference in 2006. The subject of the conversation was like this "No, I'm not really looking for storage. We're using EMC and I'm not allowed to switch to anything else. Sorry, it's a political thing". I still get phone calls all the time. I must get at least an email a week from them. Their unsubscibes don't work. My Outlook rules can seem to block their emails.

[ejward]

I looked at Compellent about a year ago. It wasn't that much more than Equallogic at the time. The reason we went with Equallogic was because I knew more companies using Equallogic than Compellent. Actually, I didn't know anyone using it at the time. Then I ran into an old friend after we had bought Equallogic.

Prices have come down for Equallogic since Dell bought them. A chassis filled with 16 1TB dives is about $48,000 if that helps. With RAID 50, it gives you 12 TB usable.

[virtualbot]

Oh my god!!

[virtualbot]

That was definitely some useful piece of info. It kinda seems from the conversations tht compellent is a wise idea to go with!!