From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heinz Mauelshagen Subject: Re: [PATCH] dm-thin: Add data block size limits to the Documentation Date: Wed, 24 Jul 2013 11:32:00 +0200 Message-ID: <51EF9F10.3030304@redhat.com> References: <1374588196-9510-1-git-send-email-cmaiolino@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1374588196-9510-1-git-send-email-cmaiolino@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids On 07/23/2013 04:03 PM, Carlos Maiolino wrote: > $data_block_size can't be any arbitrary number, i.e. its value should be between > 64K and 1G. Also, it should be a multiple of 64K. The limits 64K and 1G are correct and enforced by the pool constructor in the target. Blocksize is _not_ a multiple of 64K; it has to be power of 2. Thus 64K,128K,256K,512K and 1G are valid block sizes for the pool with the current pool constructor limits enforced. -- lvmguy > Add this information to the dm-thin documentation in order to let users know > which values they must use. > > Signed-off-by: Carlos Maiolino > --- > Documentation/device-mapper/thin-provisioning.txt | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/Documentation/device-mapper/thin-provisioning.txt b/Documentation/device-mapper/thin-provisioning.txt > index 30b8b83..ff1629b 100644 > --- a/Documentation/device-mapper/thin-provisioning.txt > +++ b/Documentation/device-mapper/thin-provisioning.txt > @@ -104,8 +104,8 @@ primarily interested in thin provisioning may want to use a value such > as 1024 (512KB). People doing lots of snapshotting may want a smaller value > such as 128 (64KB). If you are not zeroing newly-allocated data, > a larger $data_block_size in the region of 256000 (128MB) is suggested. > -$data_block_size must be the same for the lifetime of the > -metadata device. > +$data_block_size must be between 128 (64KB) and 2097152 (1GB) and be a multiple > +of 128 (64KB), and the same for the lifetime of the metadata device. > > $low_water_mark is expressed in blocks of size $data_block_size. If > free space on the data device drops below this level then a dm event