The portion of the logical volume that is extended, if I understand Linux's
LVM correctly is not striped.

-----Original Message-----
From: Hall, Ken (IDS DCS PE) [mailto:[EMAIL PROTECTED]
Sent: Monday, February 07, 2005 12:54 PM
To: [email protected]
Subject: Re: lvreduce question


If the filesystem is striped, you can't reduce or extend it.  The number of
stripes has to match the number of physical volumes.

I've done this on Intel with reiser on Fedora Core 3, and it did work.  I
extended the volume with lvextend, did a resize_reiserfs, then used
resize_reiserfs to REDUCE the filesystem to slightly less than the original
size (for safety).  This took longer than I thought it would, given that
there was no chance that the space being removed had been used, but the
utility goes through it all anyway.  Then I ran lvreduce to reduce the
volume back to the single device boundary, and removed the second PV.
Another run of resize_reiserfs extended the FS back to the original size.

It all worked fine, but obviously, YMMV.

I specifically tried this on a new server before putting it in production
because I was curious about whether it could
be done.

You should be able to verify this easily enough.  vgdisplay -v will show the
usage of each PV in the VG.  Run the create, extend, and reduce, and see
what happens.

> -----Original Message-----
> From: Linux on 390 Port [mailto:[EMAIL PROTECTED] Behalf Of
> Little, Chris
> Sent: Monday, February 07, 2005 1:33 PM
> To: [email protected]
> Subject: Re: [LINUX-390] lvreduce question
>
>
> Yes, but because the filesystem has yet to be extended, there
> _should_ be no
> data.
>
> If the logical volume isn't striped, I don't see a problem
> with reducing the
> volume group.
>
> That being said, my recommendation would be to make a backup
> first.  There
> is danger in everything.
>
> -----Original Message-----
> From: Post, Mark K [mailto:[EMAIL PROTECTED]
> Sent: Monday, February 07, 2005 12:27 PM
> To: [email protected]
> Subject: Re: lvreduce question
>
>
> No help, but I've always wondered about this myself.  The man
> page says "Be
> careful when reducing a logical volume's size, because data
> in the reduced
> part is lost!!!" which makes me very nervous when even
> thinking about this.
>
>
> Mark Post
>
> -----Original Message-----
> From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On
> Behalf Of Hank
> Calzaretta
> Sent: Monday, February 07, 2005 12:05 PM
> To: [email protected]
> Subject: lvreduce question
>
>
> Hello,
>
> I needed to expand the size of an LVM filesystem.  I successfully ran
> vgextend and lvextend.  I have not yet resized the file
> system.  My problem
> is that I added 1 too many volumes to the LV.  My question
> is, if I run
> lvreduce, as follows:
>
>         lvreduce -L -2340M /dev/xsg1/winxs_lv1
>
> am I guaranteed that the logical extents at the end of the LV
> are the ones
> that will be removed, i.e. the ones on device "/dev/dasdbk1"
> from the list
> below.  Since I haven't yet done a filesystem resize, these
> extents are
> unused.  I suspect that is the case but I can't find anything
> in writing to
> verify it.
>
>
> Below is the output of the "lvdisplay -v" command:
>
>
> Thanks,
> Hank Calzaretta
> RR Donnelley Technology Services, Inc.
>
>
> --- Logical volume ---
> LV Name                /dev/xsg1/winxs_lv1
> VG Name                xsg1
> LV Write Access        read/write
> LV Status              available
> LV #                   1
> # open                 1
> LV Size                32.02 GB
> Current LE             8197
> Allocated LE           8197
> Allocation             next free
> Read ahead sectors     128
> Block device           58:1
>
>    --- Distribution of logical volume on 14 physical volumes  ---
>    PV Name                  PE on PV     reads      writes
>    /dev/dasdg1              586          24547852   1973778
>    /dev/dasdh1              586          7748       137092
>    /dev/dasdi1              586          500448     34685126
>    /dev/dasdj1              586          15363459   1372778
>    /dev/dasdq1              586          3031687    584205
>    /dev/dasdr1              586          2271945    1515371
>    /dev/dasds1              586          253867     1344031
>    /dev/dasdbe1             585          0          0
>    /dev/dasdbf1             585          0          0
>    /dev/dasdbg1             585          0          0
>    /dev/dasdbh1             585          0          0
>    /dev/dasdbi1             585          0          0
>    /dev/dasdbj1             585          0          0
>    /dev/dasdbk1             585          0          0
>
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