[dm-crypt] Testing TRIM with hdparm on dm-crypt

Alexander Koch mail at alexanderkoch.net
Wed Nov 9 21:25:20 CET 2011


Hi Milan,

thanks for your detailed explanations :)

After adding the offsets for LUKS and LVM I realized that I have another 
partition residing logically "in front" of the PV:

$ lsblk /dev/sdd -f
NAME                    FSTYPE      LABEL      MOUNTPOINT
sdd
├─sdd1                  ext2        boot       /boot
└─sdd2                  LVM2_member
   ├─m4vg0-root (dm-0)   crypto_LUKS
   │ └─root-crypt (dm-4) ext4        root-crypt /
(..)

Adding its size in blocks finally resulted in the correct range, and I 
saw the random noise of the encrypted testfile disappear after synced 
`rm` invocation.


> You should be also able to trace discard (and other) block requests
> using blktrace/btrace, this should be really more user friendly :)

I tried blktrace but didn't know which event to track. Supported list 
includes READ, WRITE, BARRIER, SYNC, QUEUE, REQUEUE, ISSUE, COMPLETE, FS 
and PC.


Thanks again for your help! :)


Kind regards,

lynix


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