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

[Jim Kinney]

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.
>

http://blog.backblaze.com/2009/09/01/petabytes-on-a-budget-how-to-build-cheap-cloud-storage/

45 drives in a 4U = 135TB (and a back brace!)

>
> 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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-- 
-- 
James P. Kinney III

As long as the general population is passive, apathetic, diverted to
consumerism or hatred of the vulnerable, then the powerful can do as they
please, and those who survive will be left to contemplate the outcome.
- *2011 Noam Chomsky

http://heretothereideas.blogspot.com/
*
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