Re: Full use of varying drive sizes?

[Jon Hardcastle <jd_hardcastle@yahoo.com>]

Some good suggestions here, thanks guys.

Do I >DID< imagine some built in support for making use of this space?

As a side note. when i do a repair or check on my array.. does it check the WHOLE DRIVE.. or just the part that is being used? I.e. in my case.. I have a 1TB drive but only an array multiple of 500GB.. i'd like to think it is checking the whole whack as it may have to take over some day...

-----------------------
N: Jon Hardcastle
E: Jon@eHardcastle.com
'Do not worry about tomorrow, for tomorrow will bring worries of its own.'
-----------------------


--- On Tue, 22/9/09, Majed B. <majedb@gmail.com> wrote:

> From: Majed B. <majedb@gmail.com>
> Subject: Re: Full use of varying drive sizes?
> To: "Linux RAID" <linux-raid@vger.kernel.org>
> Date: Tuesday, 22 September, 2009, 2:07 PM
> When I first put up a storage box, it
> was built out of 4x 500GB disks,
> later on, I expanded to 1TB disks.
> 
> What I did was partition the 1TB disks into 2x 500GB
> partitions, then
> create 2 RAID arrays: Each array out of partitions:
> md0: sda1, sdb1, sdc1, ...etc.
> md1: sda2, sdb2, sdc2, ...etc.
> 
> All of those below LVM.
> 
> This worked for a while, but when more 1TB disks started
> making way
> into the array, performance dropped because the disk had to
> read from
> 2 partitions on the same disk, and even worse: When a disk
> fail, both
> arrays were affected, and things only got nastier and worse
> with time.
> 
> I would not recommend that you create arrays of partitions
> that rely
> on each other.
> 
> I do find the JBOD -> Mirror approach suggested earlier
> to be convenient though.
> 
> On Tue, Sep 22, 2009 at 3:58 PM, John Robinson
> <john.robinson@anonymous.org.uk>
> wrote:
> > On 22/09/2009 12:52, Kristleifur Dađason wrote:
> >>
> >> On Tue, Sep 22, 2009 at 11:24 AM, Jon Hardcastle
> >> <jd_hardcastle@yahoo.com>
> wrote:
> >>>
> >>> Hey guys,
> >>>
> >>> I have an array made of many drive sizes
> ranging from 500GB to 1TB and I
> >>> appreciate that the array can only be a
> multiple of the smallest - I use the
> >>> differing sizes as i just buy the best value
> drive at the time and hope that
> >>> as i phase out the old drives I can '--grow'
> the array. That is all fine and
> >>> dandy.
> >>>
> >>> But could someone tell me, did I dream that
> there might one day be
> >>> support to allow you to actually use that
> unused space in the array? Because
> >>> that would be awesome! (if a little hairy re:
> spare drives - have to be the
> >>> size of the largest drive in the array
> atleast..?) I have 3x500GB 2x750GB
> >>> 1x1TB so I have 1TB of completely unused
> space!
> >>
> >> Here's a thought:
> >> Imaginary case: Say you have a 500, a 1000 and a
> 1500 GB drive. You
> >> could JBOD the 500 and the 1000 together and
> mirror that against the
> >> 1500GB.
> >>
> >> Disclaimer:
> >> I don't know if it makes any sense to do this. I
> haven't seen this
> >> method mentioned before, IIRC. It may be too
> esoteric to get any
> >> press, or it may be simply stupid.
> >
> > Sure you can do that. In Jon's case, a RAID-5 across
> all 6 discs using the
> > first 500GB, leaving 2 x 250GB and 1x 500GB free. The
> 2 x 250GB could be
> > JBOD'ed together and mirrored against the 500GB,
> giving another 500GB of
> > usable storage. The two md arrays can in turn be
> JBOD'ed or perhaps better
> > LVM'ed together.
> >
> > Another approach would be to have another RAID-5
> across the 3 larger drives,
> > again providing an additional 500GB of usable storage,
> this time leaving 1 x
> > 250GB wasted, but available if another 1TB drive was
> added. I think this may
> > be the approach Netgear's X-RAID 2 takes to using
> mixed-size discs:
> > http://www.readynas.com/?p=656
> >
> > Cheers,
> >
> > John.
> > --
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> >
> 
> 
> 
> -- 
>        Majed B.
> --
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> 


      
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