Re: fstrim and Luks / dm-raid
Hi.
On Sat, Oct 05, 2019 at 02:52:55PM +0200, Erwan David wrote:
> I've got a computer with 3 SSD in RAID5 (dm-raid) containing a LUKS
> partition, then a lvm
> Is fstrim useful in suc a case ?
It's disabled by default, but you can enable by setting
"issue_discards=1" in lvm.conf, and by adding "discard" option to your
crypttab. There's no SSD-specific mdraid configuration.
Also, [1].
> or on mylaptop without the raid, but with LUKS and LVM ?
I use fstrim on my laptop since wheezy, and this particular laptop has
LVM on top of LUKS PV.
> Should I add the discard option in fstab ?
It's safe only if your SSD firmware is sane and does not corrupt your
data while processing TRIM with NCQ enabled.
For instance, some noname Chinese SSD (ADATA, for instance) can corrupt
your filesystem in such circumstances, Samsung 850 PRO should not.
Manual fstrim invocation seems to be safe.
Put an emphasis on "should" in the sentences above.
> Or an equivalent in > mdadm.conf or cryptsetup.conf ?
See above.
Reco
[1] https://wiki.debian.org/SSDOptimization
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