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SSDs: The New King of the Data Center?
Nerval's Lobster writes "Flash storage is more common on mobile devices than data-center hardware, but that could soon change. The industry has seen increasing sales of solid-state drives (SSDs) as a replacement for traditional hard drives, according to IHS iSuppli Research. Nearly all of these have been sold for ultrabooks, laptops and other mobile devices that can benefit from a combination of low energy use and high-powered performance. Despite that, businesses have lagged the consumer market in adoption of SSDs, largely due to the format's comparatively small size, high cost and the concerns of datacenter managers about long-term stability and comparatively high failure rates. But that's changing quickly, according to market researchers IDC and Gartner: Datacenter- and enterprise-storage managers are buying SSDs in greater numbers for both server-attached storage and mainstream storage infrastructure, according to studies both research firms published in April. That doesn't mean SSDs will oust hard drives and replace them directly in existing systems, but it does raise a question: are SSDs mature enough (and cheap enough) to support business-sized workloads? Or are they still best suited for laptops and mobile devices?"
TL/DR: "The relative cost of the two configurations shows that over-all there are cost savings using the SSD instances"
at least for their use-case (Cassandra).
At work we also use SSDs for a couple terabyte Lucene index with great success (and far cheaper than getting a couple TB of DRAM spread across the servers instead)
By switching to SSD's on a data intensive web application, I got 20 times speed improvement - from 20 hits per second to 400. I trust SSDs more than physical spindles any day.
The question is really going to be what kind of shape the drives will be in a year or so from now after 12+ months of constant heavy usage. The usage profile in consumer computers is a lot different from that in a server, and the server workload's going to stress more of the weakest areas of SSDs. And when it comes to manufacturer or lab test results, simple rule: "The absolute worst-case conditions achievable in the lab won't begin to approximate normal operating conditions in the field.". So, while SSDs are definitely worth looking at, I'll let someone else to do the 24-36 month real-workload stress testing on them. There's a reason they call it the bleeding edge after all.
We have hundreds of SSDs in production servers. We couldn't survive without them. For heavy database workloads, they are the silver bullet to I/O problems, so much so that running a database on regular disk has become almost unimaginable. Why would you even try to do that?
You have to remember that enterprise level storage isn't a single set of drives holding the data, it's a hierarchy of different technologies depending upon the speed of data access required. Since SSDs arrived they've been used at the highest access rate end of the spectrum, essentially using their low latency for caching filesystem metadata. I can see that now they are starting to replace the small, high speed drives at the front end entirely. However, it's going to be some time before they can even begin to replace the storage in the second tier and certainly not in the third tier storage where access time isn't an issue but reliable, "cheap" and large drives are required. Of course, beyond this tier you generally get on to massive robotic tape libraries anyway, so SSDs will never in the foreseeable future trickle down to here.
Agrajag: "Oh no, not again!"
The enterprise class SSDs are not the same as the "consumer" ones: http://www.anandtech.com/print/6433/intel-ssd-dc-s3700-200gb-review
Don't be surprised if you stick a "consumer" grade one to a heavily loaded DB server and it dies a few months later.
Fine for random read-only loads.
And some consumer grade SSDs aren't even consumer grade (I'm looking at you OCZ: http://www.behardware.com/articles/881-7/components-returns-rates-7.html ).
Pricing really needs to come down on these things. A single drive can easily cost as much as a server, and when you're talking about RAID setups, forget it. It's still much more effective to use magnetic drives and use aggressive memory caching for performance, if you really need that.
Another 3 to 5 years this idea might have more traction for companies that aren't Facebook or Google, but right now, SSD costs too much.
I think that the wide range adoption of server SSDs also shows how far server installations have progressed toward eliminating all single points of failure.
In the passt HA and 'five nines' was something only done by a few niches, like telephony provider switches or banking big iron. Today it is common in many cloud installations and most sizeable server setups. A single component failing will not stop your service.
If your business can support the extra cost for the SSDs, a failing drive will not stop you and the performance of the service will see great improvements anyway. The power savings may even make the SSD not so costly after all.
This is being driven primarily by increasing levels of virtualisation, which turns everything into a largely random-write disk load, pretty much the worst case scenario for regular old hard disks.
Up to 2.5 times faster
Ah, "up to." Marketing's best friend.
systemd is Roko's Basilisk.
SAS doesn't really get you anything useful with an SSD. The extra chaining isn't that important, because it's easy to get enough SATA sockets to put one in each drive bay. There's no mSATA equivalent for denser storage, and if you really need the extra speed then why not go all the way and get something like FusionIO cards that hang directly off the PCIe bus?
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I work for an Australian hosting company and we have deployed the SolidFire all-SSD SAN for our cloud-based hosting (shared, reseller, cloud/virtual server), the major benefits of an all-SSD storage solution speak for themselves: far lower I/O wait time, huge IOPS numbers - in SolidFire's case 250,000+ distributed IOPS in our current configuration. We've recently shifted from the HP SAS-based Lefthand SAN offering up to 15,000 IOPS to the new SolidFire all-SSD SAN and the team behind SolidFire are partly from the Lefthand operation from HP, so there's some good know-how there. The article is quite broad in its content, for big data applications SSD SAN storage is still incredibly more expensive ($/GB) than SATA or SAS based SANs - our SolidFire was a huge investment. Many hosting providers are now switching to all-SSD based servers for the performance benefits, however the drawback is primarily total storage capacity of course. For example a typical VPS node using local storage with 10 x SATA drives can get up to 4TB of usable RAID-protected storage. The numbers for an all-SSD node in RAID configuration would be much lower in capacity and suitable higher in cost. Its important to note that many people view SSDs as desktop only hardware, which is fundamentally incorrect, as there are many units out there that offer write longevity much longer than needed (5-10+ years). For many server based applications (not big-data purposes), SSDs are, and will become the predominant choice among many hosting companies. Not every provider can afford the investment of an enterprise grade SAN, however the speed of development from Intel and Samsung will mean the $/GB will drop steeply and disk sizes will increase exponentially (like what we've with SATA in the past 5 years).
They have to say up to. Reads and writes towards the inside of the chip are slower then they are towards the outside of the chip. I don't think anyone makes a constant linear velocity SSD.
SSD's might not be used as primary storage, yet. The cost of using a lot of SSD's in a SAN is still too high. However, that doesn't mean that SSD technology is not being used. Many systems started using SSD's as Read/Write caches or highspeed buffers, etc. The PCIe SSD cards are popular in highend servers. This is one way that Oracle manages to blow away the competition when benchmarks are compared. They put a PCIe SSD cards into their servers and use them to run their enterprise database at lightning speeds! ZFS can use SSD's as Read/Write caches although you had better battery backup the Write cache!.
Depending on a particular solution, a limited number of SSD's in a smaller NAS/iSCSI RAID setup can make sense for something that needs some extra OOMF! But I don't yet see large scale replacement of traditional spinning rust drives with SSD's yet. In many cases, SSD's only make sense for highly active arrays where reads and writes are very heavy. Lots of storage sits idle and isn't being pounded that hard.