Hello Radosław,

There may be a place for an option that puts back zeros where zeros were
read as Bastian is requesting, but it is clear that this code would break the
current behavior of sparse file (sparse volume) handling, which is not desirable.

Best regards,
Kern



On 08/06/2012 08:35 PM, Radosław Korzeniewski wrote:
Hello,

2012/7/27 Bastian Friedrich <bastian.friedrich@collax.com>

the attached patch modifies Bacula's behavior during restore of data that
originates from a block device with the "sparse" option set. Instead of simply
seeking to the requested file position, zero bytes are written to the
file/device in chunks of 64k.


Well, what about a thin-provisioned volumes/disks?

The main problem is that someone was used a sparse=yes option with raw-device (lvm) which do not support thin-provisioning (something like sparse file on fs).

If a user will have a thin-provisioned volume that he can successfully use sparse=yes option without any garbage and can use it even with a vm image. A lot of enterprise users use this functionality in their storage environments. We shouldn't change this behavior without a deep discussion about pros. and cons. of it.

All we should do is to explicitly add a correct information (even a warning) to the documentation. No change in code, please.

--
Radosław Korzeniewski
radoslaw@korzeniewski.net


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