Lately, there has been a lot of buzz in the enterprise storage arena about whether so-called “enterprise drives” are really any better than plain-Jane hard drives in Enterprise applications. This came to a head with the controversial findi…

A few assumptions:
-The target storage system needs to be able to contain 10 TB worth of data
-The storage system needs to be scalable
-The storage system needs optimal data security vs. costs. (of course data triplication is nice, but most of us, libraries including, don’t have that much money)
-The storage system needs to be web-accessible
-The storage system needs to be disaster-proof

If you are searching for something that should fit these needs as well, this is probably your best solution:

Two seperate servers stored at seperate locations (cheapest way of avoiding data-loss through distasters). Configure the first server for RAID5EE (hot spare integration) and the second for RAID60 (SAN). Use 500GB enterprise drives for your first server and 500GB nearline drives for the SAN. Make the first server backup daily to the SAN. Perform nightly checkdisks so you can determine when new spare drives should be ordered. And last, but not least, make sure you have the money to buy a whole new server environment within 7 years.

That isn’t anywhere near cheap, but it’s most cost-effective almost 100% guarantee for preserving your data. This configuration doesn’t necessarily have to be optimal for the next generation of hardware you will buy.

Perhaps noone is helped with this, but I’ll be happy if it just helps Someone. Just some (nearly offtopic) sidepoints, for cheap home RAID’s, check the Intel Matrix RAID solution. For future archiving, pay attention to holographic storage development. I’ll save you the other random findings of my study

Of course not. Radically different technologies, as you know.

Packing twice the blocks on the same physical spindle as onother drive built with the SAME TECHNOLOGY will and does result in twice the number of bad blocks for the same physical damage to, or inperfection in the platter.

There is no free lunch, and you do indeed get what you pay for. It doesn’t show up in this study, because this study doesn’t take into account the primary advantage of enterprise diks, which is twice the phyical media allocated to each block using the same platter technology as their consumer grade cousions.

Even if FC, SAS and SATA all do inded have similar rates of failure for their mechansisms, which I wouldn’t doubt, if you’re willing to pay for RAID redundancy, why not media redundancy teh blocks on your platter?

Apart from the advantages on the contoller board of FC or SAS, what your paying for is twice the saftey of the data contained on those blocks. If you don’t care about what lives on those blocks, I guarantee you someone will when they go missing.

Just my two cents.

-ted

Of course I’m talking about data corruption due to bad blocks, and the fact that only drive-wide hardware failures were taken into account in this study is the basis of my point.

Robin tried to dismiss my point as being architectural and not real world, yet my whole point is that this study misses some critical aspects of real world experience, which is that when you go to fetch data, and you can’t get it because the blocks are bad, or you can’t rebuild a portion of the data after a failure because the block are bad, then whoever needed that data is going to consider it to be a failture, regardless of whether the RAID controller labels the disk as failed or not.

Data corruption = failure. Anyone who tells you diffrent is trying to sell you something.

-ted

On a current “big iron” application, we made the chang from SATA drives to Fibre drives before implementation this past year. Storage costs increased exactly 100% for the same amount of storage, not 400 to 600% as has been suggested. So, if you’re thinking of doubling or “tripling” up on SATA, look at the costs also.

Facility costs on “big iron” projects are huge. The costs to double, or triple, up the space to stand up SATA and the added costs for cooling these drives over a period of years can be staggering.

Now if your just looking at a simple “one for one” replacment Fibre with SATA, with the same size of storage in the end, then it’s worth looking into because storage costs could be reduced by half.

As an example our costs could be reduced from $4 million to $2. I’ll be taking a look, and will have to make a complicated business decision.

Given the comparatively low cost of storage, isn’t RAID 1, 4 and 5 outdated now? Doesn’t RAID 10 give better performance and more redundancy? Given the lower cost of storage isn’t it the epitomy of cheap to still be using RAID 5 in server or SAN systems?

Let me also address the myth that “enterprise” drives are somehow better than “consumer” grade drives. Anyone who knew what they were speccing when designing storage systems knew damned well they weren’t paying for fewer failures, they were paying for performance. Faster spindle speeds, lower seek times, lower transfer rates, more write cache and higher throughput were the name of the game. Anyone thinking they were buying lower failure rates was on a fool’s errand.

I would also like to address that silliness that RAID is pointless because you still have a single point of failure in the controller. Well, Duh! That’s why the RAID config info is stored on the drives and not in the card or any other volatile memory. If a card fails, it can be replaced without losing data. Also keep in mind that RAID isn’t the end-all and be-all for data security. It is at best one piece of a comprehensive stratagy that should include other things like backups, redundant storage and archiving

Let me also put things into perspective with mfg published MTBF and MTTF rates. As I stated above 1,000,000 hours is 114 years. The published numbers are ESTIMATES based on predictive TESTING. If they were to actually to run real-world tests on samples to get statistical numbers, we would still be putting 20MB MFM and RLL 5.25″ drive in our systems while we waited for manufacturers to complete their testing.

Let me take the opportunity to put it into geek speak since I just by chance, watched Star Wars the other night “..So you see Luke what I told you IS true… from a certain point of view.” Interpreting statistics is a fool’s game. They are guidelines based on a certain set of conditions and not facts.

I absolutely agree with magicalbob’s last two paragraphs on redundancy.

When talking about MTBF, not enough emphasis was put on the duty cycle of each system. In my experience SATA systems simply buckle under constant heavy IO load with drives popping just like popcorn. Under light to medium load I would expect SATA and SCSI/FC to show similarly lower failure rates. Then again I may be just the exception…