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[2]: RAID Z
by computeruser on Mon 18th Jan 2010 23:52 UTC in reply to "RE: RAID Z"
computeruser
Member since:
2009-07-21

ZFS is not a standard (unlike, say RAID6). It's an implementation. Far worse, it's a patent encumbered implementation of a triple parity RAID level.

There is no standard detailing RAID-6, just a widely accepted definition.

ZFS happens to implement something with similar redundancy characteristics to RAID-5 and RAID-6 and also implements triple parity.

You'll amazed to hear that most of the world doesn't use OpenSolaris.

So? That doesn't change that OpenSolaris supports triple parity right now. Since OpenSolaris has networking support, including CIFS, iSCSI, and NFS serving, it can still be useful to those who don't currently use OpenSolaris.

As far as I remember, OpenSolaris' modified grub cannot boot from ZFS RAID. (And nothing beats losing your boot record + kernel on a production machine, right?)

ZFS is not the only way to provide redundancy for a boot partition.

Reply Parent Score: 3

RE[3]: RAID Z
by gilboa on Tue 19th Jan 2010 07:56 in reply to "RE[2]: RAID Z"
gilboa Member since:
2005-07-06

There is no standard detailing RAID-6, just a widely accepted definition.

ZFS happens to implement something with similar redundancy characteristics to RAID-5 and RAID-6 and also implements triple parity.


Semantics.
I can use a on-board RAID5 controller (read: soft-RAID) built array and move it from Windows to Linux and back, it's a standard.

So? That doesn't change that OpenSolaris supports triple parity right now. Since OpenSolaris has networking support, including CIFS, iSCSI, and NFS serving, it can still be useful to those who don't currently use OpenSolaris.


... And yet, its still irrelevant for the rest of the world.

ZFS is not the only way to provide redundancy for a boot partition.


So?

- Gilboa

Reply Parent Score: 2

RE[4]: RAID Z
by dvzt on Tue 19th Jan 2010 11:50 in reply to "RE[3]: RAID Z"
dvzt Member since:
2008-10-23

My god, you are a deluxe troll.

"As far as I remember, OpenSolaris' modified grub cannot boot from ZFS RAID."

False. OpenSolaris and Solaris 10 have the ability to boot from mirrored ZFS pool for ages.

"I can use a on-board RAID5 controller (read: soft-RAID) built array and move it from Windows to Linux and back..."

I can't imagine how you can possibly try to compare HW and SW based RAID. Anyway, I can import my zpool on Solaris, FreeBSD, Linux/FUSE and OSX. With Linux's LVM or md-based RAID - no luck. I also can control onboard RAID controller from Solaris with raidctl command.

"...it's a standard."

Wow, Linux fanboy talks about standards. You might want to talk about when will Linux be POSIX compliant or when will it finally get standards-compatible NFS4 implementation? So far, Linux is ignoring standards whenever possible.

"... And yet, its still irrelevant for the rest of the world."

Even if that was true, I don't understand why people like you have the need to bash (Open)Solaris. You don't like it - don't use it.

"Gee, why can't I use ZFS on my Linux severs?"

Because GPL fascists made the license to mandate it. Why do OpenSolaris and FreeBSD exchange code both ways, but Linux can not?

What I don't understand is, why under any Solaris or ZFS related post has to be some BS like this. You are upset that there is technically superior OS to Linux, go hack the kernel all day, go petition Linus for stable API/ABI or do something meaningful. I certainly don't comment on every Linux-related post about what a pile of crap it is, although I could.

Reply Parent Score: 7

RE[4]: RAID Z
by computeruser on Tue 19th Jan 2010 15:12 in reply to "RE[3]: RAID Z"
computeruser Member since:
2009-07-21

I can use a on-board RAID5 controller (read: soft-RAID) built array and move it from Windows to Linux and back, it's a standard.

You can move a RAID array using a certain implementation and move it to another operating system that also supports that implementation. But people generally do not need to do this in the real world. (And there isn't really a standard filesystem worth running between Windows and Linux.)

Different hardware and software RAID implementations are implemented in different ways; they are in no way standardized other than they all implement some form of mirroring, striping, and striping with parity (for those supporting RAID5/6). Linux dmraid understands some of these proprietary formats.

... And yet, its still irrelevant for the rest of the world.

OpenSolaris is not irrelevant to the rest of the world - it's freely downloadable and usable, just like that "Linux" thing that was irrelevant in the early 90s. And the new ZFS features in OpenSolaris will be in Solaris at some point.

I personally use Linux md RAID1, RAID10, and RAID6, and these arrays only work on Linux.
I don't run any Linux applications on the server other than those needed to share the filesystems / arrays. I could provide the same services using OpenSolaris (or Windows, or FreeBSD...) And OpenSolaris has the huge advantage of ZFS.

"ZFS is not the only way to provide redundancy for a boot partition.

So?
"
You mentioned the inability to boot from ZFS RAID with GRUB as if it were a major disadvantage that makes ZFS unusable in a production environment. This is not the case.

Reply Parent Score: 2

RE[4]: RAID Z
by CodeMonkey on Tue 19th Jan 2010 16:29 in reply to "RE[3]: RAID Z"
CodeMonkey Member since:
2005-09-22

I can use a on-board RAID5 controller (read: soft-RAID) built array and move it from Windows to Linux and back, it's a standard.


Having a driver for a particular piece of hardware in 2 OS's does not make a standard. Common, sure, but standard, no. Now, if you could build the RAID 5 array on one brand and version of controller and the use that same array with a different brand and version controller, that would be more standard like.

Various RAID levels aren't like a standards spec to follow, more like an abstract description of an algorithm.

Let's say RAID5 is like a V6 engine in a car:

V6 = Use 6 cylinders arranged in a 2x3 V configuration.
There's no reason to expect a Honda V6 to fit in place of a Ford V6. Just because they're both a V6 doesn't make V6 a spec standard, just a common way to design an engine.

RAID5 = use 1 disk worth of parity information distributed and staggered across the entire array.
There's no reason to expect a RAID5 array built with an Adaptec controller to plug right in and work in place of an LSI built RAID5 array with an LSI controller. Just because they're both a RAID5 array doesn't make RAID5 a spec standard, just a common way to build a disk array.

Reply Parent Score: 3