Re: LVM performance vs direct dm-thin
"Stuart D. Gathman" <[email protected]>
| Newsgroups | gmane.linux.lvm.general |
|---|---|
| Message-ID | <[email protected]> |
On Sun, 2022-01-30 at 11:45 -0500, Demi Marie Obenour wrote: > On Sun, Jan 30, 2022 at 11:52:52AM +0100, Zdenek Kabelac wrote: > > > > > Since you mentioned ZFS - you might want focus on using 'ZFS-only' > > solution. > > Combining ZFS or Btrfs with lvm2 is always going to be a painful > > way as > > those filesystems have their own volume management. > > Absolutely! That said, I do wonder what your thoughts on using loop > devices for VM storage are. I know they are slower than thin > volumes, > but they are also much easier to manage, since they are just ordinary > disk files. Any filesystem with reflink can provide the needed > copy-on-write support. I use loop devices for test cases - especially with simulated IO errors. Devs really appreciate having an easy reproducer for database/filesystem bugs (which often involve handling of IO errors). But not for production VMs. I use LVM as flexible partitions (i.e. only classic LVs, no thin pool). Classic LVs perform like partitions, literally using the same driver (device mapper) with a small number of extents, and are if anything more recoverable than partition tables. We used to put LVM on bare drives (like AIX did) - who needs a partition table? But on Wintel, you need a partition table for EFI and so that alien operating systems know there is something already on a disk. Your VM usage is different from ours - you seem to need to clone and activate a VM quickly (like a vps provider might need to do). We generally have to buy more RAM to add a new VM :-), so performance of creating a new LV is the least of our worries. Since we use LVs like partitions - mixing with btrfs is not an issue. Just use the LVs like partitions. I haven't tried ZFS on linux - it may have LVM like features that could fight with LVM. ZFS would be my first choice on a BSD box. We do not use LVM raid - but either run mdraid underneath, or let btrfs do it's data duplication thing with LVs on different spindles. _______________________________________________ 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/