Filesystems

btrfs

btrfs scrub

As a copy-on-write (COW) filesystem btrfs can compensate some errors from the underlying storage

check checksum on READ
fix logical block if valid copy is available (RAID1, RADI5/&, DUP)
07.2022 no force WRITE-VERIFY possible -> look downwards

btrfs resize

btrfs filesystem show -d
btrfs filesystem resize -500m /dev/mapper/ubuntu--vg-root/@subvolume

btrfs snapshot size

to show all snapshots enable quotas

    [root@localhost ~]# btrfs quota enable /btrfs/
    [root@localhost ~]# 
    [root@localhost ~]# btrfs qgroup show  /btrfs/

systemd handling

create for all btrfs filesystems a regulary scrub timer.

for p in $(lsblk -nflo FSTYPE,MOUNTPOINT | awk '$1=="btrfs"{print $2}'); do systemctl enable --now "btrfs-scrub@$(systemd-escape -p "$p").timer"; systemctl start "btrfs-scrub@$(systemd-escape -p "$p").service"; done

the manual way of creating is eating the correct escape.

luks

on-the-fly encryption of existing file system

#reduce filesystem to gain space for the luks header
btrfs filesystem resize -32m /mounted_filesystem
#create on the fly encrypted filesystem
cryptsetup reencrypt --encrypt --reduce-device-size 32m /dev/plaintext_device

ATA/SMART

hdparm

write-verify

with hdparm you can activate the write-verify -R1 handling, if the drive has got this feature. Most consumer devices do not have this. Otherwise hdparm is more for the temporary set of AAM or APM, ATAsecurity, DCO, e.g. To disable use -R0

/dev/sdb: [SSD]
 multcount     =  0 (off)
 IO_support    =  1 (32-bit)
 readonly      =  0 (off)
 readahead     = 256 (on)
 geometry      = 31130/255/63, sectors = 500118192, start = 0

/dev/sda: [HDDD]
 multcount     = 16 (on)
 IO_support    =  1 (32-bit)
 readonly      =  0 (off)
 readahead     = 256 (on)
 geometry      = 60801/255/63, sectors = 976773168, start = 0

If it tells you write-read-verify = 2 then the feature is enabled

smartmontools

the smartmontools contains mainly two features: the smart daemon and the smartctl tool. smartctl controls the SMART features of a drive, smartd usually surveille and run tests as a daemon with it.

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