W dniu 2014-10-25 o 14:50, Zdenek Kabelac pisze:
Is there any way to make LVM2 tools wipe added/freed LV space or plans to add
such functionality?
lvm.conf devices { issue_discard = 1 }
See it that fits your need ?
Note: when using this option - vg/lvremove becomes 'irreversible'operation.
issue_discard seems to require "underlying storage support" which is probably not available in
common RAID/SATA/SAS/DRBD scenarios. Universal, open (source) solution would be better here probably
(with hardware alternatives where possible).
When LVM based storage is used for guest virtual disks, it is possible that
after resizing/snapshoting LV, disk data fragments from one guest will be
visible to other guest, which may cause serious security problems if not wiped
somehow[...]
thin provisioning with zeroing enabled for thin-pool -Zy is likely better option.
Sounds interesting. Is it stable solution for production systems? Does it perform not worse than
"regular" preallocated LV?
Note: you could obviously implement 'workaround' something like:
lvcreate -l100%FREE -n trim_me vg
blkdiscard /dev/vg/trim_me
(or if disk doesn't support TRIM - dd if=/dev/zero of=/dev/vg/trim_me....)
lvremove vg/trim_me
If I understand correctly, in this scenario, guest data may still be present outside "cleaned" LV
(i.e. data that was saved outside LV in snapshot LV during backups). If so - cleaning should be
probably done transparently by LVM "software" layer, even without "underlying storage support".
Regards,
Pawel
IB Development Team
https://dev.ib.pl/
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