Four X25-E Extreme SSDs Combined In Hardware RAID

theraindog writes "Intel's X25-E Extreme SSD is easily the fastest flash drive on the market, and contrary to what one might expect, it actually delivers compelling value if you're looking at performance per dollar rather than gigabytes. That, combined with a rackmount-friendly 2.5" form factor and low power consumption make the drive particularly appealing for enterprise RAID. So just how fast are four of them in a striped array hanging off a hardware RAID controller? The Tech Report finds out, with mixed but at times staggeringly impressive results."

Comments

Re:Oh good

[spazdor]

'cause regular hard drives usually survive 5 years in an enterprise environment, yep yep.

Actually, that RAID card seems more interesting

[the_humeister]

A 1.2 GHz processor with 256 DDR2 memory? Holy crap! That's faster than my new Celeron 220! And the perennial quesion: can this thing run Linux?

Re:Actually, that RAID card seems more interesting

[default luser]

Actually, I felt that the limiting factor was probably the craptastic single-core Pentium 4 EE they used to run all these benchmarks.

What, you shove thousands of dollars worth of I/O into a system, and run it through the paces with a CPU that sucked in 2005? I'm not surprised at all that most tests showed very little improvement with the RAID.

What I want to see

[XanC]

Is 4 of these in a RAID-1, running a seek-heavy database. Nobody does this benchmark, unfortunately.

Re:What I want to see

[afidel]

Good controllers do read interleaving where every other batch of reads is dispatched to a separate drive.

Re:What I want to see

[Anonymous Coward]

RAID5 has terrible random write performance, because every write causes a write to every disk in the array. it's VERY easy to saturate traditional disks random write capabilities with raid5/6. So, it's rightly avoided like the plague for heavily hit databases.

I'm not certain how much of the performance hit is due to latencies of disks. So i feel it would be an interesting test to also see raid5 database performance.

Also, Raid1 (or 10 to be more fair when comparing with RAID5) in a highly saturated environment. reading data should do marginally better than Raid5 since you don't lose a disk to parity--and any raid controller worth it's salt will send independent reads or round robin your read's to both disks).

Then, there is also that whole disk failure thing. It's a huge performance hit to lose a disk in RAID5. For that reason alone in a heavily hit environment it would probably be best to avoid it.

Disk failure is not an IF, but a WHEN. i Dont care what manufacturers say about MTBF's.

Re:What I want to see

[XanC]

RAID5's write performance is so awful because it requires so much reading to do a write.

I have to read from _every drive in the array_ in order to do a write, because the parity has to be calculated. Note that it's not the calculation that's slow, it's getting the data for it. So that's multiple operations to do a simple write.

A write on RAID1 requires writing to all the drives, but only writing. It's a single operation.

RAID1 is definitely faster (or as fast) for seek-heavy, high-concurrency loads, because each drive can be pulling up a different piece of data simultaneously.

Re:Oh good

[LordKaT]

'cause SSD's don't cost $300-$500 more than their spindle counterparts, yep yep.

Re:Oh good

[poot_rootbeer]

I'll be sure to do that, and replace them every 5 years when they run out of write operations.

Winchester drives, on the other hand, use a time-honored complex system of delicate moving parts, and last virtually forever. They certainly do not start experiencing sudden failures if kept in continuous service for more than 5 years.

Re:Oh good

[ChienAndalu]

Make that 228 years.

Life expectancy 2 Million Hours Mean Time Before Failure (MTBF)

Hint: learn about "wear leveling"

If I keep my current 15K drives that long

[Shivetya]

I will be surprised.

See, in the enterprise environment that I work in the majority of our big hardware is leased. I am quite willing to use what I can to maintain performance and reliability. That being said my system is built entirely on 15K drives of various sizes. I am not worried about five years or so of read/write that SSD drives have, all I want to see is a track record. I expect to replace most of the drives I have now within five years so this "five year limit" many like to toss out is immaterial to me. Reliability over that lifetime is of more importance.

Besides, the nice benefit of SSD drives is I don't need special enclosures (read: ones that can handle the torque these puppies can put out)

Re:paging benefits?

[tom17]

I really don't get this obsession with page files these days. Say you have 4GB ram and an 4GB page file. Memory is cheap these days, so rather than using 4GB of (relatively slow) SSD, why not just get another 4GB ram?

Redundant Array of what?

[telchine]

This is a very expensive solution. What part of Redundant Array of Inexpensive Disks don't they understand?

Re:Redundant Array of what?

[Ioldanach]

That's right. Marketing switched "Inexpensive" for "Independent" years after the term was coined, because they couldn't convince people to buy their non-Inexpensive disks for RAID use as easily under the old meaning.

Re:Redundant Array of what?

[afidel]

Dude, 4 of these drives can keep up with my 110 spindle FC SAN segment for IOPS. Here's a hint, 110 drives plus SAN controllers is about two orders of magnitude more expensive than 4 SSD's and a RAID card. If you need IOPS (say for the log directory on a DB server) these drives are hard to beat. The applications may be niche, but they certainly DO exist.

Re:Oh good

[spazdor]

Your enterprise environment must not be hitting its drives very hard.

Where SSDs is in disk operations that are usually lagged out by seek times; a big unwieldy database that gets a lot of writes and no downtime, for instance, is happiest when it lives on a striped SSD array.

Coincidentally, this is exactly the type of workload which is most likely to shorten a magnetic drive's life.

Re:Oh good

[FauxPasIII]

> 'cause SSD's don't cost $300-$500 more than their spindle counterparts, yep yep.

Hint: Enterprise storage purchasing often looks at dollars/IOPS rather than dollars/GB.

Comparisons a little unfair in places

[heffrey]

It seemed a little unfair that they only used the nice hardware RAID controller with the Intel SSDs. I would have liked to see them use it with all the other disks to get a more level playing field.

Re:paging benefits?

[guruevi]

SSD shouldn't be for paging. That would become very expensive (even with wear leveling) if you have a minimal amount of RAM (say 256M) to run large (say 16G) operations. It would also be slow since you have the overhead of whatever bus system your hard drive/ssd is connected to.

Technically hard drives aren't supposed to be paging either, it's just a cheap and simple trick to avoid having people pay a lot for (expensive) RAM or have their programs crash when occasionally they run out of RAM. However if your system is paging heavily it's better and faster with more RAM.

Anecdote: I worked at a place once where cheap ($500) hardware was sold as dedicated SQL/IIS servers (you could fit 10 of them in 5U) and a lot of customers thought they could run whatever they wanted (Microsoft ran MSN for a whole country of one for a while) in them but they only supported a maximum of 2G RAM (4G according to BIOS but the modules back then were too expensive). Of course PHB just said: let them swap and besides the heavy slow downs they ran fairly fine. Well, those heavy users all crashed their software-RAID's in less than a year (the heavy load made Windows get the RAID system out of sync and then you had the first hard drive fail). The temperature was fine but simply swapping out was too much for the cheap hard drives (Maxtor and Seagate) and they all failed.

Re:Oh good

[neoform]

I must be doing something wrong then. Should I put my computer in the freezer when I'm not using it or something, like, to keep it fresh longer?

Re:Oh good

[CMonk]

I think you're comparing against SATA drives. People that worry about IOPS are normally using FC drives which are much more closely aligned in price with SSDs. (btw, been a while since I was in the market for FC drives)

Re:New acronym: RAVED?

[CompMD]

No, its got a cooler acronym, RAVEN: Redundant Array of Very Expensive Not-disks-but-some-silly-stack-of-flash-memory-chips.

Re:Oh good

[DMalic]

It's obvious sarcasm.

Re:Oh good

[horza]

MTBF is a highly inaccurate way to show how long you should expect a drive to live. The whole Seagate Fiasco is a prime example of why NOT to believe them.

Misuse of a statistical figure is a problem with those misinterpreting it. Obviously things have changed since schools taught the difference between the mean, the mode, the median, and the minimum. If I run an ISP then MTBF is useful for me to calculate costs, both in replacements and labour costs. It's not supposed to be a measurement for consumers though that will be buying single unit quantities.

Buying a hard drive is like buying a washing machine. If I'm lucky it will go on practically for ever. On the other hand if I'm unlucky it could die tomorrow. As Piranhaa says, there are too many variables. All I can go on is that if it comes with a garauntee of 3 years then I assume the manufacturers have designed it to mostly exceed that figure otherwise they would end up losing money on the product. I still have to ensure I have a contingency plan in case it breaks down.

Phillip.

Re:paging benefits?

[ErikZ]

I'm Betaing Windows 7. Before going to bed I set up a swap partition for it. After getting up the next morning and checking, it was full.

I have *no idea* what W7 put in there while I was sleeping.

Re:paging benefits?

[illumin8]

I'm Betaing Windows 7. Before going to bed I set up a swap partition for it. After getting up the next morning and checking, it was full.

I have *no idea* what W7 put in there while I was sleeping.

In any modern operating system, including Windows , swap isn't just used for out of physical memory conditions. It's also used to "page out" portions of the operating system and libraries, shared objects, dlls, etc., that aren't being used at the moment. This actually speeds your system up by allowing more memory to be used as disk read/write cache.

I've looked at Linux boxes with 64GB of memory in them and only using 25% of that. I usually get asked by someone, "wasn't 64GB enough? Why is there some usage in swap right now?" It's normal, I explain. The kernel just pages out sections of Linux that aren't needed, to free up more RAM for filesystem caching.

I think perhaps Windows 7 just has a more aggressive way of doing this, probably because if you need to use some obscure Windows Directmedia SuperDRM doubleplusgood Plugin X, it's just as fast to reload it out of swap into memory as it is to load the binary from disk. But 99% of home users will never load that plugin so it can stay safely swapped out, giving you more precious memory for applications and disk cache.