2016-01-01 5:25 GMT+08:00 Zdenek Kabelac <zkabelac@redhat.com>: > You should be aware of thin-pool limits. > > i.e. ATM it's bad plan to use more then say 16 LVs in parallel for > a single thin-pool LV - it cannot be used in some massive parallel system > for its current locking mechanism. Is it LVM or dm-thin kernel target's limit? And, is there any reference about the "16 LVs" and the locking issue? (why 16 LVs?) > There is even sequencing problem with creating snapshot in kernel target > which needs to be probably fixed first. > (the rule here should be - to never create/allocate something when > there is suspended device - and this rule is broken with current thin > snapshot creation - so thin snap create message should go in front > to ensure there is a space in thin-pool ahead of origin suspend - will > be addressed in some future version....) > > However when taking snapshot - only origin thin LV is now suspended and > should not influence rest of thin volumes (except for thin-pool commit > points) Does that mean in future version of dm-thin, the command sequence of snapshot creation will be: dmsetup message /dev/mapper/pool 0 "create_snap 1 0" dmsetup suspend /dev/mapper/thin dmsetup resume /dev/mapper/thin > minor warning - snapshot is not a backup - although it might look like it is > :). Yes, we know it, thanks :) Ming-Hung Tsai _______________________________________________ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
