On 23 Nov 2020 at 12:50, Samuel Sieb wrote: Subject: Re: Clone logical volume using dd To: users@xxxxxxxxxxxxxxxxxxxxxxx From: Samuel Sieb <samuel@xxxxxxxx> Date sent: Mon, 23 Nov 2020 12:50:46 -0800 Send reply to: Community support for Fedora users <users@xxxxxxxxxxxxxxxxxxxxxxx> > On 11/23/20 1:02 AM, Michael D. Setzer II via users wrote: > > dd bs=1M if=$localback |lzop -c - > /mnt/local$localpath$localimagename > > > > I use lzop for compression of image, since it gives good compress and is > > considerable faster than gzip. > > > > Note: Since it does copy all blocks, it is best to clear the currently > > unused blocks before hand. Long ago, did an image of a disk with clean > > install of Fedora 3 on 80GB disk. Image created was 12G in size > > compress. Cleared free space, and redid imaged, and size dropped to > > 2.5G. Compression does depend on what is on disk.. > > This is still not suitable for his purpose. It's not about the > compressed size, it's about the number of blocks copied. Using dd, you > are still copying *all* the unused blocks which will be really bad for a > thin LV which is the intended destination. The difference between a bit level image and an image that has to understand all aspects of the partition info. If the unused data blocks are cleared by filling with nulls, it compress to nothing. The resulting images are very similar in size. Agree, it takes longer to make the image, since it does have to read all blocks of the disk/partition, but it copies all data. Using a program that determines what needs to be backed up and what doesn't may or may not copy everything at some point. With the disk bit level images, one could restore to a new disk, and not have to do any prep of creating the partition setup, since that was already included in the image. With partitions, that isn't an issue. I had linux and windows on my classroom machines, and sometimes imaged one system to all the other machines using udpcast with bit level image. Also, had options to be able to restore the windows image in about 10 minutes to its partition from the local extra partition. So, just another option. > _______________________________________________ > users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx > To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx > Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx +------------------------------------------------------------+ Michael D. Setzer II - Computer Science Instructor (Retired) mailto:mikes@xxxxxxxx mailto:msetzerii@xxxxxxxxx Guam - Where America's Day Begins G4L Disk Imaging Project maintainer http://sourceforge.net/projects/g4l/ +------------------------------------------------------------+ _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/users@xxxxxxxxxxxxxxxxxxxxxxx
