天空вℓσи∂ [Unemployed edition] @skyblond@social.cleverlibre.org

Wait, what?

Cygwin can detect my tape drive and put it to /dev/st0?

Now I'm going to read the 9th chapter of tar manual.

Also I noticed the JVM's impl of SHA3-256 doesn't perform well. It's kind of 150MB/s and can't saturate my tape drive which can read 160MB/s.

I have no issue with Bouncy Castle's impl which is purely in Java.

I thought native impl is better. Why? (I tried Java 21 LTS, no improvement)

Finished two tape cartridges. One more to go.

But at least I think my software is working and usable. Although I notice HPE include utility tools that functionally similar to mine.

Anyway, for anyone who use LTFS with LTO 5 and later tapes, you may have a try:

https://github.com/hurui200320/OfflineArchiveManagement

Despite TeraCopy has a better GUI, it actually faster than ltfscopy.

The ltfscopy simply calls other program like copy (on Windows, or cp on Linux), then call md5sum twice to get original file hash and target file hash, all in sequence. Which I think you can calculate the hash when you copying it, or just calculate the two md5 checksum at the same time.

With a 330GB file, my SSD can read up to 300MB/s, and LTO6 tape drive can read up to 160MB/s. I can save ~18 minutes just by doing it smarter.

PS: TeraCopy do support SHA3-256 but it can only handle ~80MB/s, which is a huge shame. I have to use Blake3 to speed things up.

ok, I just found out that I don't need ltfscopy to ensure files are copied correctly.

I can use TeraCopy, it will make sure files are correct. Then I'll use my code to calculate hash and store in a database.

Who need filesystem attributes? LOL

I noticed my tape drive with ltfscopy, can wrtie 160MB/s consistently, but only read 60MB/s when verifying (read 300MB/s from my local SSD, using md5sum).

Later I'll read it from my own code and see how fast it can go.

I developed a kind-of-secure workflow when archiving things to tape. Where I select files and copy them to a second-hand tape to see how compression working. When I finally done, I keep a local storage and write then to a new tape. By using ltfscopy with `-v` option, I can make sure the files are copying correctly. Then I run my own tools on the tape to get SHA3-256 (which implemented by BouncyCastle, should be able to handle 160MB/s). Then I can verify the first copy on that second hand tape using my own tool. If everything goes right, I can make the third copy without `-v` option since I know the correct SHA3 generated by my code.

Now I'll have three copies of the same data, one with second-hand HPE MP tape, one with new HPE MP tape, and one new IBM BaFe tape.

Just notice how picky lto tapes are. Winter is fine, and the room temperature ranges from 20 C to 30 C, with 20% RH.

Summer is difficult. 40C with 90% RH.

I can't wait to see my tapes become a solid chunk of films and become unreadable

IBM gives two label stickers per tape. How generous!

Now my HPE tapes will be labeled by IBM stickers 😋

While HPE didn't enclose any label stickers in the package, the logo itself looks like a good place to write notes 😂

Another post-install issue is where to get tapes. There are second-hand LTO6 tapes costing around 10 USD, which basically is a blindbox. You never know the condition of the tape until you get it.

The brand new LTO6 tape is around 30 USD each. Guaranteed in excellent condition, but expensive. Considering I'll store the same file on 3 tapes to ensure safety, that's not cheaper than a HDD. (But with HDD, now I only have a unraid to check the files are good, I have no back up )