, 2 min read
Wiping Disks
Original post is here eklausmeier.goip.de/blog/2017/03-20-wiping-disks.
How fast can you wipe a complete disk? For this I dumped zeros to a MS Windows partition based on an SSD formatted with NTFS.
[root@i7 ~]# time dd if=/dev/zero of=/dev/sda1 bs=1M
dd: error writing '/dev/sda1': No space left on device
81920+0 records in
81919+0 records out
85898297344 bytes (86 GB, 80 GiB) copied, 182.699 s, 470 MB/s
real 3m2.703s
user 0m0.033s
sys 0m43.470s
It was a real pleasure to get rid of MS Windows after just 3 minutes ;-)
Once more, second partition on SSD formatted with NTFS.
[root@i7 ~]# time dd if=/dev/zero of=/dev/sda2 bs=1M
dd: error writing '/dev/sda2': No space left on device
147015+0 records in
147014+0 records out
154155352064 bytes (154 GB, 144 GiB) copied, 326.108 s, 473 MB/s
real 5m26.110s
user 0m0.097s
sys 1m21.503s
[root@i7 ~]# time dd if=/dev/zero of=/dev/sdb1 bs=4M
128459+0 records in
128459+0 records out
538796097536 bytes (539 GB, 502 GiB) copied, 5404.54 s, 99.7 MB/s <--- from kill -10
dd: error writing '/dev/sdb1': No space left on device
238467+0 records in
238466+0 records out
1000202043392 bytes (1.0 TB, 932 GiB) copied, 11876.6 s, 84.2 MB/s
real 197m56.647s
user 0m0.000s
sys 15m49.763s
From the man-page of dd:
Sending a USR1 signal to a running 'dd' process makes it print I/O statistics to standard error and then resume copying.
For example, in above scenario I used
kill -10 12523
Signal numer 10 is SIGUSR1, see /usr/include/bits/signum.h, or
$ kill -l
1) SIGHUP 2) SIGINT 3) SIGQUIT 4) SIGILL 5) SIGTRAP
6) SIGABRT 7) SIGBUS 8) SIGFPE 9) SIGKILL 10) SIGUSR1
11) SIGSEGV 12) SIGUSR2 13) SIGPIPE 14) SIGALRM 15) SIGTERM
16) SIGSTKFLT 17) SIGCHLD 18) SIGCONT 19) SIGSTOP 20) SIGTSTP
21) SIGTTIN 22) SIGTTOU 23) SIGURG 24) SIGXCPU 25) SIGXFSZ
26) SIGVTALRM 27) SIGPROF 28) SIGWINCH 29) SIGIO 30) SIGPWR
31) SIGSYS 34) SIGRTMIN 35) SIGRTMIN+1 36) SIGRTMIN+2 37) SIGRTMIN+3
38) SIGRTMIN+4 39) SIGRTMIN+5 40) SIGRTMIN+6 41) SIGRTMIN+7 42) SIGRTMIN+8
43) SIGRTMIN+9 44) SIGRTMIN+10 45) SIGRTMIN+11 46) SIGRTMIN+12 47) SIGRTMIN+13
48) SIGRTMIN+14 49) SIGRTMIN+15 50) SIGRTMAX-14 51) SIGRTMAX-13 52) SIGRTMAX-12
53) SIGRTMAX-11 54) SIGRTMAX-10 55) SIGRTMAX-9 56) SIGRTMAX-8 57) SIGRTMAX-7
58) SIGRTMAX-6 59) SIGRTMAX-5 60) SIGRTMAX-4 61) SIGRTMAX-3 62) SIGRTMAX-2
63) SIGRTMAX-1 64) SIGRTMAX
Here is another test with an USB 3 Seagate 2 TB hard disk, previously it had ext4:
[root@C ~]# time dd if=/dev/zero of=/dev/sdc1 bs=1M
dd: error writing '/dev/sdc1': No space left on device
1907729+0 records in
1907728+0 records out
2000397795328 bytes (2.0 TB, 1.8 TiB) copied, 21845.9 s, 91.6 MB/s
real 364m5.890s
user 0m1.020s
sys 47m33.056s
Just for clarification, it is irrespective of the previous underlying filesystem if you use dd on the whole disk. dd will happily wipe everything and just write blocks to the disk.
Added 09-Dec-2019: Another test with an Elitebook 840 G3 SSD:
root@elitebook /root# time dd if=/dev/zero of=/dev/sda bs=4M
18806+0 records in
18806+0 records out
78878081024 bytes (79 GB, 73 GiB) copied, 194.874 s, 405 MB/s
19826+1 records in
19826+1 records out
83158360064 bytes (83 GB, 77 GiB) copied, 205.777 s, 404 MB/s
28373+1 records in
28373+1 records out
119007076352 bytes (119 GB, 111 GiB) copied, 297.393 s, 400 MB/s
63167+2 records in
63167+2 records out
264945287168 bytes (265 GB, 247 GiB) copied, 676.438 s, 392 MB/s
86331+2 records in
86331+2 records out
362102145024 bytes (362 GB, 337 GiB) copied, 929.764 s, 389 MB/s
dd: error writing '/dev/sda': No space left on device
122096+2 records in
122095+2 records out
512110190592 bytes (512 GB, 477 GiB) copied, 1320.58 s, 388 MB/s
real 22m0.588s
user 0m0.407s
sys 8m46.578s