The Storage Tipping Point

Funny he mentioned System/38, which largely eliminated users' storage worries, then says that company's rep never heard of it. Funny cuz they still sell it: IBM i. I posted a link [1] to original system on his site. It got so many things right in a business machine it was hard to believe. That old design still has better security and reliability than Windows or Linux boxes. Most AS/400 deployments I run into just don't... have... downtime... They also pretty much manage themselves.

I'd like to see FOSS do designs like that [minus the interface & API]. The labor advantage might lead to something pretty awesome. Meanwhile, they keep building complexity on top of UNIX architecture with a few stragglers on better OS architectures. Not much hope there. Fortunately, CHERI (capability) and SAFE (tags) are each building on mechanisms System/38 used for software reliability and security. An academic team or company might build something great on top of it. Still holding out some hope!

[1] http://homes.cs.washington.edu/~levy/capabook/Chapter8.pdf

The article says that log-structured apps and filesystems conflict with underlying SSDs, because those are doing similar things and the two don't play well together. But then it says that "products that already incorporate log structured I/O will have a definite advantage" in the future. How can they have an advantage if they're conflicting with the storage layer? Is this a contradiction, or am I missing something?

Yup, storage is going to change a lot. RAID is nearly dead. That means a whole lot of failure detection and correction needs to be reimplemented elsewhere in the stack. We'll also need to build storage layers that can deal with the crazy performance profile of SMR hard drives (at least, until SSD's are cheaper).

Wait till memresistors get here. That will basically eliminate the distinction between ram and disk.

https://en.wikipedia.org/wiki/Memristor#1808

"They can potentially be fashioned into non-volatile solid-state memory, which would allow greater data density than hard drives with access times similar to DRAM, replacing both components.[14] HP prototyped a crossbar latch memory that can fit 100 gigabits in a square centimeter,[8] and proposed a scalable 3D design (consisting of up to 1000 layers or 1 petabit per cm3).[66] "

I was under the impression that the storage model in the system/38 was part of what was carried forward into the as400. Not the capability model, as much as the lack of "files" because everything is just persistent objects/segments.

Is that not the case?

But I'm not really sure how this by itself solves the problems of modern SSD's. Problems caused by two things, the differing segment/page sizes between the upper layers (OS/filesystem/database/etc) and the need to rewrite static portions of the SSD in order to wear level the entire address space. (and to a lesser extent the need to update small portions in the middle of existing pieces of data).

Its the second part that seems to be forgotten by lots of people suggesting alternatives to the current storage stack. Whats really necessary is a higher level communications protocol between the flash and the filesystem. One that provides the metadata to the ssd about the sizes of individual "objects" so that they may be keep together as atomic units. That way the flash layer knows if a write is to a larger object, or a new object itself that can be managed separately.

Good to see Robin Harris' article on the front page of HN (we live in the same small town and a mutual friend introduced us).

A little off topic from the article: I think the biggest tipping point is the decreasing cost of cloud storage because large companies like Google do so much of their time critical processing with data in RAM (spread over many servers) and these servers can re-purpose a lot of their disk I/O capability to service low cost cloud storage.

I think the storage company Nimble may have figured this out.