Re: [linux-lvm] [External] Re: The feasibility of implementing an alternative snapshot approach
Zhiyong Ye <[email protected]>
| Newsgroups | dev.linux.lists.linux-lvm |
|---|---|
| Message-ID | <[email protected]> |
Hi Zdenek, Thank you for your patience and explanations. I learned a lot from our discussions and thank you again for your help. Regards Zhiyong On 1/10/23 6:18 AM, Zdenek Kabelac wrote: > Dne 09. 01. 23 v 7:21 Zhiyong Ye napsal(a): >> Hi Zdenek, >> >> Thank you for your detailed answer. >> >> For the thin snapshot I will use the latest version of kernel and lvm >> for further testing. I want to use both snapshot methods (thin and >> thick) in the production environment. But if the thick snapshot is >> only still in the maintenance phase, then for thick lv I have to see >> if there is any other way to accomplish the snapshot function. > > FYI - there are still some delays with up-streaming of the latest > improvement patches - so stay tuned for further speedup gains & IO > throughput with thin provisioning) > > By the maintenance phase for old thick snapshot I mean - the development > of the existing thick snapshot target is basically done - the format is > very ancient and cannot be changed without major rewrite of the whole > snapshot target as such - and that's what we've made with newly > introduced thin-provisioning target which addressed many shortcomings of > the old dm-snapshot target. > >> I use lvm mainly for virtualized environments. Each lv acts as a block >> device of the virtual machine. So I also consider using qemu's own >> snapshot feature. When qemu creates a snapshot, the original image >> used by the virtual machine becomes read-only, and all write changes >> are stored in the new snapshot. But currently qemu's snapshots only >> support files, not block devices. > > Depending on the use-case it might matter to pick the best fitting > chunk-size. > i.e. if the changes are 'localized' in the filesystem areas to match > thin-pool chunks (also selection of the filesystem itself might be part > of equation here) - even if you use snapshots a lot, you may eventually > get better result with bigger chunks like 128k or even 256k size instead > of default 64K. > > Regards > > Zdenek > _______________________________________________ linux-lvm mailing list [email protected] https://listman.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/