Linked by Thom Holwerda on Mon 18th Jan 2010 16:57 UTC, submitted by wanker90210
Hardware, Embedded Systems ACM's latest journal had an interesting article about RAID which suggested it might be time for triple parity raid. "How much longer will current RAID techniques persevere? The RAID levels were codified in the late 1980s; double-parity RAID, known as RAID-6, is the current standard for high-availability, space-efficient storage. The incredible growth of hard-drive capacities, however, could impose serious limitations on the reliability even of RAID-6 systems. Recent trends in hard drives show that triple-parity RAID must soon become pervasive."
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RE[6]: RAID Z
by Kebabbert on Wed 20th Jan 2010 10:17 UTC in reply to "RE[5]: RAID Z"
Kebabbert
Member since:
2007-07-27

Gilboa, you are hilarious. Are you sure you are not SEGEDUNUM, he keeps repeating weird stuff, like ZFS requires several GB of RAM to start - even though several people explained that is not true, he keeps claiming that.



Regarding your ZFS "rampant layering violation", that Linux kernel developer Andrew Morton called ZFS (now why would a Linux developer call ZFS something like that?). Ive heard that BTRFS is doing something similar with it's layers, does someone know more on this layering violation by BTRFS?

I dont really understand why you have something against a superior product, because of a different design. If you see a product with different design, but the product is best on the market, compared to a product with standard design but the product is inferior - which product do you choose? Do you refuse to use a database application if it is not using the standard three layer model (DB, logic, GUI)? If a product is not using standard programming languages, but instead is using something esoteric such as Erlang - do you refuse to use the product (even though the product is best om the market)? I understand your reasoning if ZFS were inferior, but almost everyone agree that ZFS is the best filesystem out there. So, if a product is best, but has a different design - how can the design matter to you? It is only the result that matters to most people. If something is best, then it is best. No matter the design, the price, or whatever. It is best.

ZFS has tried to get rid of old assumptions and redesign filesystems from scratch, targeted to modern devices. And that is a bad thing? When the first chip was invented with superior performance to transistors - you would refuse to use chips because they were different?

The main ZFS architect Bonwick explains why ZFS has different layer design, his point is that it is not necessary to use unnecessary layers - you can optimize a layer away if you are clever enough. If you are not clever enough, you continue to use the standard solution:
http://blogs.sun.com/bonwick/entry/rampant_layering_violation




Regarding your "ZFS is OS lockin, patent issues" etc. First of all, ZFS is not OS lockin. There are other OS than Solaris that use ZFS. Wrong again.

Second. How can you say ZFS is lockin, when the code is open and out there? If SUN goes bankrupt, we have access to the ZFS code and can continue development. What happens if your hardware raid vendor goes bankrupt? Do you expect your hardware raid to continue development?

Which is most lockin, a hardware raid controller (that needs device drivers to an OS, you can not move your discs to another controller, nor to another OS) or ZFS (you can compile open ZFS code to every OS you want, and move your discs freely between the OSes, even with different endianness). Hardware raid disks can not be moved to different OSes, and if they use different endianness, you are screwed. ZFS can move discs between Apple Mac OS X, FreeBSD, Solaris, OpenSolaris, and every other OS that compiles ZFS - even between different CPU architectures with different endianness! You can not do this with hardware raid - hardware raid is lockin, you are forced to wait for drivers to your OS, you can not do anything, you have to wait for the vendor makes something. ZFS is not lockin, but hardware raid is lockin.




Man, you are just plain wrong in almost everything. The things you say are not even factually correct. It is like "In my opinion, that 2m guy is shorter than the other 1.5m guy" - but that is simply not true, factually. You can say "I dont like ZFS" - but your reasons to do so are false. Hardware raid is the most lockin there is, you can not do shit, only the vendor can do something. You dont have access to the BIOS code, you have nothing. If the vendor bankrupts, you can ditch your card.

And hardware raid is less safe than ZFS. My friend who is CTO for a small company, lost two raids due to bugs in hardware raid BIOS. they confirmed the bug but are not releasing patches yet. This was one year ago, I dont know what happened since then.

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