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From: Robin Bowes <robin-lists@robinbowes.com>
To: Christopher Smith <csmith@nighthawkrad.net>
Cc: Sebastian Kuzminsky <seb.kuzminsky@gmail.com>,
	Robin Bowes <robin-lists@robinbowes.com>,
	linux-raid@vger.kernel.org
Subject: Re: Best way to achieve large, expandable, cheap storage?
Date: Thu, 20 Oct 2005 11:23:30 +0100	[thread overview]
Message-ID: <43577022.5010306@robinbowes.com> (raw)
In-Reply-To: <43420091.9060601@nighthawkrad.net>

Christopher Smith said the following on 04/10/2005 05:09:
> Yep, that's pretty much bang on.  The only thing you've missed is using 
> pvmove to physically move the data off the soon-to-be-decomissioned 
> PVs(/RAID arrays).
> 
> Be warned, for those who haven't used it before, pvmove is _very_ slow.

I've just been re-reading this thread.

I'd like to just check if I understand how this will work.

Assume the following setup (hypothetical).

VG:
big_vg - contains /dev/md1, /dev/md2; 240GB

PV:
/dev/md1 - 4 x 40GB drives (RAID5 - 120GB total)
/dev/md2 - 4 x 40GB drives (RAID5 - 120GB total)

LV:
big_lv - in big_vg - 240GB

Filesystems:
/home - xfs filesystem in big_lv - 240GB

Suppose I then add a new PV:
/dev/md3 - 4 x 300GB drives (RAID5 - 900GB total)

I want to replace /dev/md1 with /dev/md3

I use pvmove something like this:

# pvmove /dev/md1 /dev/md3

When this finishes, big_vg will contain /dev/md2 + /dev/md3 (1020GB 
total). /dev/md1 will be unused.

big_lv will still be using just 240GB of big_vg.

I then use lvextend to increase the size of big_lv

big_lv will now use all 1020GB of big_vg.

However, the /home filesystem will still just use 240GB of big_lv

I can then use xfs_growfs to expand the /home filesystem to use all 
1020GB of big_lv.

Have I missed anything?

R.
-- 
http://robinbowes.com

If a man speaks in a forest,
and his wife's not there,
is he still wrong?

  reply	other threads:[~2005-10-20 10:23 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-09-30 13:20 Best way to achieve large, expandable, cheap storage? Robin Bowes
2005-09-30 13:29 ` Robin Bowes
2005-09-30 18:28   ` Brad Dameron
2005-09-30 19:20     ` Dan Stromberg
2005-09-30 18:16 ` Gregory Seidman
2005-09-30 18:34   ` Andy Smith
2005-10-02  4:36 ` Christopher Smith
2005-10-02  7:09   ` Tyler
2005-10-03  3:19     ` Christopher Smith
2005-10-03 16:33   ` Sebastian Kuzminsky
2005-10-04  4:09     ` Christopher Smith
2005-10-20 10:23       ` Robin Bowes [this message]
2005-10-20 11:19         ` Gregory Seidman
2005-10-20 11:41           ` Robin Bowes
2005-10-21  4:42           ` Christopher Smith
2005-10-21 16:48             ` Gil
2005-10-21 20:08               ` Robin Bowes
2005-10-21  4:40         ` Christopher Smith
  -- strict thread matches above, loose matches on Subject: below --
2005-10-27 19:12 Andrew Burgess

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