ChatGPT on dd block size

Posted on 2023-12-09 [Saturday] by Jay Jay

I was pretty impressed by this:

ChatGPT 3.5

User:
if you’re going to use dd to write random data over a hard drive device what block size is best?

ChatGPT:
When using the dd command to write random data over a hard drive device, the choice of block size can impact the performance of the operation. The optimal block size can vary depending on the specific circumstances, but there are some general guidelines you can follow.

A common recommendation is to use a block size that is a multiple of 4 KB (4096 bytes), which is often the physical sector size of modern hard drives. This alignment can improve performance because it matches the underlying hardware.

Here’s an example of using dd with a block size of 4 KB:

$ dd if=/dev/urandom of=/dev/sdX bs=4K

Replace /dev/sdX with the actual device name you want to overwrite, and adjust the block size (bs) according to your needs.

However, keep in mind that there is no one-size-fits-all answer, and performance may vary depending on your specific hardware and use case. You might want to experiment with different block sizes to see what works best for your situation.

Additionally, when overwriting a hard drive for security reasons (e.g., before decommissioning or selling it), consider using tools specifically designed for secure erasure, such as shred or wipe. These tools often implement more sophisticated algorithms to ensure data is thoroughly and securely overwritten.

vDSO (virtual dynamic shared object)

Posted on 2023-12-07 [Thursday] by Jay Jay

Today I learned about the vDSO on the Linux man page: vdso(7) — Linux manual page. It’s a facility for replacing syscalls with normal user-space function calls for things like getting the time of day for better performance.

More chromium woes

Posted on 2023-11-23 [Thursday] by Jay Jay

Man my chromium browser has been giving me a lot of grief lately. Two times so far I needed to reboot to fix the problem. This is the third time and rebooting is always such a hassle. :(

-------------------
Thu Nov 23 20:20:54 [bash:5.2.15 jobs:0 error:0 time:0]
jj5@charisma:/home/jj5
$ chromium 
[1123/202056.945777:ERROR:elf_dynamic_array_reader.h(64)] tag not found
[1123/202056.945823:ERROR:elf_dynamic_array_reader.h(64)] tag not found
Trace/breakpoint trap (core dumped)
-------------------

More chromium woes

Posted on 2023-11-20 [Monday] by Jay Jay

So it seems that my trouble with chromium is not over. Today a new twist. Thank God I still have Firefox! I will try updating and rebooting again, but can’t do that at the moment.

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Mon Nov 20 10:11:08 [bash:5.2.15 jobs:0 error:0 time:0]
jj5@charisma:/home/jj5
$ chromium 
[4085207:4085207:1120/101109.660602:ERROR:policy_logger.cc(157)] :components/enterprise/browser/controller/chrome_browser_cloud_management_controller.cc(163) Cloud management controller initialization aborted as CBCM is not enabled.
[4085207:4085238:1120/101109.672026:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672044:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672050:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672055:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672061:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672064:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672075:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672079:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672082:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672086:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672091:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672098:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672107:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672115:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672132:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672147:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672154:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672159:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672165:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672169:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672173:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672178:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672185:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085238:1120/101109.672193:ERROR:login_database.cc(1100)] Password decryption failed, encryption_result is 2
[4085207:4085207:1120/101109.758579:ERROR:cmd_buffer_helper.cc(141)] ContextResult::kFatalFailure: CommandBufferHelper::AllocateRingBuffer() failed
Fontconfig error: Cannot load default config file: No such file: (null)
[1120/101109.770548:ERROR:elf_dynamic_array_reader.h(64)] tag not found
[1120/101109.770620:ERROR:elf_dynamic_array_reader.h(64)] tag not found
30185030681216:error:1000007d:SSL routines:OPENSSL_internal:CERTIFICATE_VERIFY_FAILED:../../third_party/boringssl/src/ssl/handshake.cc:393:
Trace/breakpoint trap (core dumped)
-------------------

// 2023-11-22 jj5 – UPDATE: a reboot fixed this problem.