It doesn't matter what RAID level you use, rm -rf / will still dutifully delete all of your data for you.

Repeat after me, RAID is not a backup.

The numbers I provided are actually generously overstated, as you'll only hit them when you're 100% loading everything.

When you're doing something useful (like playing a game), you don't have all 4+ CPU cores loaded 100%, nor do you have all 2+ GPUs 100% loaded, so their actual power usage is significantly lower than their max TDP. It is extremely difficult to put 100% load on a highly parallel resource like a multi-core CPU or (multiple) modern GPUs, and to do both at the same time (while doing anything useful) is exponentially more difficult, and extremely system specific. Even with a stationary target like a console, developers still struggle to fully utilize all of the hardware after 5+ years of experience with it.

Are you running quad SLI? No? Then your computer isn't using 700W of power. Typical gaming rigs these days rarely break 200W, even though they may be sold with 1000W (or more) PSUs.

Even with four GTX 980s in quad SLI, they would only be drawing 4*165W (= 660W) at peak. Even with a $1000 CPU (~130W TDP) and a dozen drives you're still going to be extremely hard pressed to get anywhere close to 700W.

Also, here's a 865W UPS for $180, that's pretty typical pricing and hugely oversized for a single machine.

Amazon? Yeah, that was a good move.

It's not so much a trend as it is an unavoidable problem with increasing densities of SSDs. As you shrink the process size to fit more stuff in the same space, the durability goes down. As you change from SLC to MLC to TLC to fit more stuff in the same space, durability goes down. Substantial technological advances will be required to produce a 20T SSD with both acceptable durability and cost.

In comparison, shortscreen monitors (often mislabeled as widescreen) are a trend which has no logical or technical underpinning.

Absolutely not. Even 100 RAIDed HDDs (in any RAID type) will struggle to match the IOPS achieved with a single SSD.

Typical IOPS for a 7200 RPM HDD: 80

Typical IOPS for a modern consumer level SSD: 20,000-100,000

http://en.wikipedia.org/wiki/IOPS

Now you're talking about something different. The OP specifically said upgrading a kernel (not a distribution). You can take the kernel from RHEL 6 and run it on RHEL 5 (in fact, this is exactly what Oracle does with OEL).

Userspace backwards compatibility is a whole different can of worms. For userspace, you're at the mercy of any libraries you dynamically link against, few promise binary compatibility indefinitely. Your Linux native hello world program compiled in 1991 will still run, unmodified, on today's distros, as it doesn't require any libraries. For more complex programs, you're looking at shipping local copies of the libraries you depend on, either via static linking, or copies of the dynamically linked libraries. The latter option can even be done after the fact.

Of course, if you still have the source, things are much easier. A simple recompile is often sufficient to fix any dynamic linking issues, source compatibility is broken far less often than binary compatibility. While not every old Linux program may run out of the box, it should be fairly trivial to make them work on a modern distro.

Now, if you want to talk about running old programs on new versions of Windows, let's talk about IE6 on Windows 8, without using virtualization. Good luck with that!

The #1 rule of the kernel is that you cannot break userspace. Care to provide an example?

The one thing that would break is out of tree kernel modules that were never upstreamed. If you depend on those, then you screwed up.

You probably tried to draw more power than the UPS is rated for. The UPS will cut power at this point to protect itself.

Even 10 years ago 1280x720 would be pathetic... and you're telling me it doesn't even hit 60 fps?

I run about 90% of the systems I manage in RAID 10 (there are a few oddballs in there, some only support 2 drives, those are RAID 1, and there's a few where I don't care about performance, but do care about drive space, those run RAID 5/6). The real world performance difference of RAID 10 over a single drive is very large. Assuming a four drive RAID 10 array, expect between 2x and 4x improvement in both random and sequential read/write performance.

WIth that in mind, at $dayjob, we run a lot of VMs. Before SSDs were affordable, we could usually fit between 6 and 8 VMs on a single host (with 4x or 6x 7200 rpm drives in RAID 10) before they became unusably slow, with tons of time spent in disk wait. CPU time and memory usage were rarely limiting factors. As soon as we started deploying SSDs, the only problem was running out of space. Right now we have over 50 VMs running on a single 8x SSD RAID 10 array, and it's blindingly fast.

There's a similar story with databases. Back before SSDs were affordable, we bought a machine with enough RAM to keep the entire database cached in memory, as it was just too slow to run off of 15k RPM SAS drives. On a fresh boot, we'd still need to precache the database into memory, and with said HDDs, that's a job that took something like 10 minutes and was almost entirely disk bound. We recently upgraded that machine to SSDs, and the same precache task now takes under 30 seconds.

As for home users, well that's a different story. Personally I think it's downright irresponsible to run any system with a single drive (HDD or SSD), but the overwhelming majority of existing machines with a single drive suggest that my opinions on this matter are not widely held.

I guess my issue with your proposal is that I just can't see very many cases where it's practical. The low end of the market is dominated by Laptops/Desktops/Tablets/whatever that cost under $500 and all have only a single drive, as an extra $100 for another drive is going to be a dealbreaker most of the time (if another drive would even physically fit). The high end of the market where performance is critical, is completely dominated by SSDs. You can read countless stories of big companies replacing full racks (42U) of HDDs with 1U or 2U of SSDs. I guess somewhere in the middle there is a small set of people who:

• store a lot of non-media* files (over 500G or 1T)
• are not overly concerned with performance
• have the technical know-how to set up and maintain a RAID array
• are significantly more concerned with reliability than most
• are still relatively cost-sensitive

Those people would probably be better served by a 4x HDD RAID 10 array than a 2x SSD RAID 1 array.

* If you're storing media files on SSDs, you either have too much money to burn, or zero sense. They're huge and 99% of the time are read/written sequentially.

Most workloads are in fact dominated by small, mostly random, reads and writes, which is why SSDs are just that much faster in the majority of cases.

If you're talking about mainly sequential reads, then the situation for the four RAID1 HDDs is even grimmer. RAID1 provides virtually no speedup for single reader sequential reads, as to do so would require tons of seeks from the drives (which as we know, HDDs fail at), or an extremely large file and very large stripe size (and also a matching amount of memory for intermediate buffers). Most RAID1 implementations don't even bother trying.

Having said that, HDDs are substantially better at sequential reads and writes than random ones, and if your workload really, truly is dominated by sequential operations (and it probably isn't), you can generally match the performance of a single SSD with a RAID10 of roughly a dozen HDDs (or a RAID0 of half a dozen, but say goodbye to reliability). This ignores the fact that a dozen of even the cheapest HDDs is substantially more expensive than an SSD, due to actual unit cost, the extra power draw, the extra physical space required for them, the extra HBA(s) to plug the drives into, the extra manpower to install/manage them and the extra manpower to deal with them when they die.

There are still reasons to use HDDs, but performance is absolutely not one of them. It's not even close. Take it from someone who manages several hundred HDDs + SSDs.

Where by "a lot of", you mean less than 1% of, right?

Typical IOPS on a 7200 RPM HDD is around 80. Typical IOPS on a garden variety SSD is 80,000. We'll be generous and assume linear speedup for the four HDDs, which gives us 320 IOPS, or 0.4% of the performance of a single SSD.

I'm glad you agree that DRM is never OK.