Category: storage / NAS / QNAP

GNU Linux – how to mount single disk failed RAID1
23.01.2021

for some reason… did ext3 on RAID1 with two disks (seagate + wd) of different sized (2TB but they (of course) are not not exactly 2TB) not sure where the problem here was 1) kernel 2) ext3 3) the disks… […]

unit of data storage – byte kilobyte megabyte gigabyte terabyte petabyte exabyte zettabyte yottabyte nonabyte doggabyte kibibyte mebibyte gibibyte tebibyte pebibyte exbibyte zebibyte yobibyte nobibyte dogbibyte
12.01.2021

Byte The term byte was coined by Werner Buchholz in June 1956,[4][13][14][b] during the early design phase for the IBM Stretch[15][16][1][13][14][17][18] computer, http://archive.computerhistory.org/resources/text/IBM/Stretch/pdfs/Buchholz_102636426.pdf backup mirror: PLANNING A COMPUTER SYSTEM BROJECT STRETCH Buchholz Campbell_102636426.pdf which had addressing to the bit and […]

LibreBoot – (how to mount luks2 encrypted volume) LVM encrypted volumes needs correct CMOS clock time – Volume Group not found – failed to read int token error parsing metadata
03.12.2020

to recover the data: how to mount luks2 encrypted volume possibility: remove harddisk, attach to sata2usb adapter, then mount on different machine like this: # unlock encrypted harddisk udisksctl unlock -b /dev/sdb5 udisksctl mount -b /dev/mapper/ubuntu–vg-root Mounted /dev/dm-1 at /media/dpm/e8cf82c0-f0a3-41b3-ab28-1f9d23fcfa72 […]

recompress video with ffmpeg to save disk space
05.04.2020

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 […]

10.01.2020

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
16.07.2019

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 […]

30.06.2019

# 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
04.02.2019

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) requirements: server: have OpenSSH installed allow root login […]

The Y2038 Problem – cars and embedded systems
23.01.2019

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
19.04.2018

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 […]

31.01.2018

REM delete all mapped network drives net use * /DELETE /Y REM map two drives net use W: “\\192.168.0.233\SharedFolderA” /persistent:yes /user:usernameA PaSsWorDA net use T: “\\192.168.0.231\SharedFolderB” /persistent:yes /user:usernameB PaSsWorDB what you need to know: windows CAN NOT establish two connects […]

19.12.2017

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 […]