[ale] They say drives fail in pairs...

[Richard Bronosky]

This is a great writeup by Alfredo Deza, one of my coworkers.
http://www.ibm.com/developerworks/library/os-zfsraidz/index.html

He did a lunch and learn at my company where he started with a common
VirtualBox OVA of OpenIndiana (that's the community fork of Open
Solaris) and added a bunch of disks, set up zfs, generated some data,
then started playing Chaos Monkey (worth a Googling) with the drives.
It was 1 hour of very convincing presentation.

On Tue, Jan 3, 2012 at 6:29 PM, Michael Trausch <mike at trausch.us> wrote:
> On 01/03/2012 04:52 PM, Lightner, Jeff wrote:
>> That confuses me.  Does ZFS have built in redundancy of some sort
>> that would obviate the need for the underlying storage to be hardware
>> RAID?  Or are you saying you'd use ZFS rather than Software RAID?
>
> Both ZFS and btrfs have redundancy capabilities built-in that
> (allegedly!) play nicely with the filesystem's built-in dynamic resizing
> volume management stuff.  Neither filesystem is "just" a filesystem, but
> aims to be a whole volume-management stack.  No more need for things
> like LVM, when all you need to do is create an fs on a single whole
> drive (no partition table) and hot-add or hot-remove it from the pool of
> storage.
>
> The other nifty thing is that they can do redundant data storage on even
> a single device, as I understand it, so that you can do things like have
> the same data on a single drive in multiple locations, which helps if
> one area of the drive goes bad.
>
> I don't use hardware RAID for anything (and I'm not likely to ever do
> so).  If I ever needed storage that went beyond what a few hard disks
> could provide, or something that needed to be larger than what I would
> trust something like ZFS or btrfs to do on their own, I would probably
> build a dedicated rack-mount box that had tens of drives in it and use
> something like RAID 10 with three stripes.
>
> There was a "DIY" guide to building such a box, along with lists of
> hardware and tools needed to build the things, and claiming something
> like 100+ TB of storage in a single box.  They're expensive in absolute
> dollars, but relatively inexpensive compared to other solutions that
> scale that far up in storage space, and they are powered by Linux
> software RAID (AFAIK).  You would use the things such that you could
> replace standalone failed drives off-line, and replace whole units in
> (ideally) only as long as it takes to power one down and install a new one.
>
> I'm not anywhere near that, yet, though.  I can only really forsee
> needing to grow to about 6 TB of reliable storage in the next two years,
> but given the high rates of change in everything around me at the
> moment, I can't really look much farther than that.
>
>        --- Mike
>
> --
> A man who reasons deliberately, manages it better after studying Logic
> than he could before, if he is sincere about it and has common sense.
>                                   --- Carveth Read, “Logic”
>
>
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.!# RichardBronosky #!.