Category: storage / NAS / QNAP

recompress video with ffmpeg to save disk space

recompressing mobile phone videos can save significant amount of (precious ssd) disk space. it is very cpu intense – so either bring massive amounts of cpu power or massive amounts of runtime 🙂 on 4x threads Core(TM) i5-4200U CPU the […]


mdadm -E /dev/sd[a-z] # -E, –examine # Print contents of the metadata stored on the named device(s). # Note the contrast between –examine and –detail. # –examine applies to devices which are components of an array, while # –detail applies […]

how to change uuid of logical lvm partitions

problem: manually changing uuids is tidious and might not yield the result you want. unfortunately have not succeeded yet with integrating an old harddisk.vdi (same uuids) back into the template vm (same uuids) – so the recommendation is: reinstall os […]


# where is what? lsblk -o “NAME,MAJ:MIN,RM,SIZE,RO,FSTYPE,MOUNTPOINT,UUID” NAME MAJ:MIN RM SIZE RO FSTYPE MOUNTPOINT UUID sda 8:0 0 838.3G 0 ├─sda2 8:2 0 837.3G 0 crypto_LUKS 23c92dca-43f2-4a55-80cf-acfecb0ca482 │ └─luks-23c92dca-43f2-4a55-80cf-acfecb0ca482 253:0 0 837.3G 0 LVM2_member aXsFmd-a5wn-tP5p-AM2k-Jmx3-Sdhn-0vT911 │ ├─centos-root 253:1 0 50G […]

remote network mount directory via ssh – sshfs

it is super slow, but for copying small files it works. if /mnt/cifs/here is owned by non-root user, also non-root users are allowed to mount. (which is rather tricky with mount cifs) # setup software apt install sshfs yum install […]

The Y2038 Problem – cars and embedded systems

in comparison to Y2K: “The issue became when it became 2000 because that would be stored as 00 in the program. This caused many to believe that say, bank software wouldn’t be able to get your money out because it […]

Samba4 on CentOS7 in under 10min – add windows file sharing user script – security – from SMB 1.0 to 2.0 – anti ETERNALBLUE EXPLOIT update trouble – SID “username” is not in a valid format – pdb_getsampwnam (tdb) error fetching database – solved

update: 2019-02: everything was fine… until you decided to update because of the EthernalBlue exploit THAT ALSO AFFECTS OPEN SOURCE IMPLEMENTATIONS OF SMB 1.0! (WTF!? WHY?), samba now miss behaves on Debian and CentOS. (scroll down for details) EternalBlue, sometimes […]


REM delete all mapped network drives net use * /DELETE /Y REM map two drives net use W: “\\\SharedFolderA” /persistent:yes /user:usernameA PaSsWorDA net use T: “\\\SharedFolderB” /persistent:yes /user:usernameB PaSsWorDB what you need to know: windows CAN NOT establish two connects […]


You might want to checkout very basic sequential write/read benchmark with dd. You might want to checkout iozone in c harddisk benchmark. this benchmark is especially useful if you need to measure how java is performing on your harddisk/filesystem/os (linux […]

Howto install and setup File Sharing Server with GNU Linux

ext3+gnu_linux+samba = fast and reliable fileserver. WARNING! Security problems Versions from Version 3.5.0 to 4.6.4 (recent in May 2017 ) are affected and need to be patched! patches are available from: Unfortunately EVEN Debian9 (!!!! GUYS FIX THAT FAST […]

debian9 stretch – basic web based ressource monitoring with collectd

checkout the tutorial: maybe cacti and co is too complicated and looks a little outdated… collectd might be just what you are looking for 🙂 “The main objective of this is to develop an easy to use and customizable […]


The Enterprise Volume Management System (EVMS) Project has the goal of providing unparalleled flexibility and extensibility in managing storage. It represents a new approach to logical volume management for Linux. The architecture introduces a plug-in model that allows for easy […]


you should setup harddisk encryption during setup. to add an encrypted /home partition afterwards might be possible but a lot more effort. scroll very down if you want to know how to encrypt an usb sticks … needless to say […]

gnu linux smart s.m.a.r.t harddisk faillure surveillance

might be also interesting: and: harddisks… are blackboxes of data – if something fails… you do not repair – you replace. 65% of all harddisk failurs can be announced with smart. wohoo! so don’t rely on it 😀 […]


btrfs is used by SUSE12 for the /root partition – where it is doing daily snapshots of the installed OS. It has more functionality built-in than just storing files. This article wants to take btrfs for a test-drive. Video Tutorials: […]

GNU Linux – recover deleted files NTFS – undelete ext3 vs ext4 – rescue accidentally deleted data files – overwritten partition table – foremost – gpart

update: extundelete works well on ext3 but kind of failed me on ext4. tools to try: get an overview: what harddisk/partition is what? lsblk; # more detailed lsblk -o “NAME,MAJ:MIN,RM,SIZE,RO,FSTYPE,MOUNTPOINT,UUID” alias harddisk=’lsblk -o “NAME,MAJ:MIN,RM,SIZE,RO,FSTYPE,MOUNTPOINT,UUID”‘ harddisk NAME MAJ:MIN RM SIZE […]