i need help to rescue my database from bitcoin core 27.1.0

[ujiko]

I explain my problem ;
i just update ubuntu 20.04 to ubuntu 22.04, but the drive where the database of the node is on a hard drive.
So i have to mount it in fstab manually and change the permissions of the hole disk.
I made a mistake, setting.json was modified when i run the new Bitcoin core and is now emty.
So i have the data, but the core ask me to download all the data since 2009!!!
Somebody on the internet told us to just copy the backup but it doesn't work, each time i launched Bitcoin core it erase all the data.
The data are secured in chainstate.back and blocks.back folders.
Can you tell me how to build a file settings.json which i could put my wallets secured too?

gilles@kohaku:/data/chainstate.back$ ls -la
total 12348044
drwxrwxr-x  2 gilles gilles  266240 sept.  9 06:18 .
drwxrwxrw- 15 gilles gilles    4096 sept.  9 07:58 ..
-rw-------  1 gilles gilles     198 déc.   6  2023 000005.ldb
-rw-------  1 gilles gilles 2162271 sept.  8 22:30 2061581.ldb
-rw-------  1 gilles gilles 2163387 sept.  8 22:30 2061582.ldb
+++++++++++++++++++++++++++++++++++++
-rw-------  1 gilles gilles 2164115 sept.  9 06:18 2118599.ldb
-rw-------  1 gilles gilles 2163548 sept.  9 06:18 2118600.ldb
-rw-------  1 gilles gilles 2163794 sept.  9 06:18 2118601.ldb
-rw-------  1 gilles gilles      17 sept.  9 06:17 CURRENT
-rw-------  1 gilles gilles       0 déc.   6  2023 LOCK
-rw-------  1 gilles gilles  676804 sept.  9 06:18 MANIFEST-2118387

gilles@kohaku:/data/blocks.back$ ls -la
total 1846196
drwxrwxr-x  4 gilles gilles    266240 sept.  9 05:16 .
drwxrwxrw- 15 gilles gilles      4096 sept.  9 07:58 ..
-rw-rw-r--  1 gilles gilles 133327254 sept.  9 01:15 blk04478.dat
-rw-rw-r--  1 gilles gilles 133427050 sept.  9 01:16 blk04479.dat
-rw-rw-r--  1 gilles gilles 133933545 sept.  9 01:17 blk04480.dat
-rw-rw-r--  1 gilles gilles 134197979 sept.  9 01:18 blk04481.dat
-rw-rw-r--  1 gilles gilles 133104428 sept.  9 02:35 blk04482.dat
-rw-rw-r--  1 gilles gilles 133646270 sept.  9 02:52 blk04483.dat
-rw-rw-r--  1 gilles gilles 134029199 sept.  9 03:11 blk04484.dat
-rw-rw-r--  1 gilles gilles 133838202 sept.  9 03:40 blk04485.dat
-rw-rw-r--  1 gilles gilles 133128723 sept.  9 03:47 blk04486.dat
-rw-rw-r--  1 gilles gilles 133565921 sept.  9 05:01 blk04487.dat
-rw-rw-r--  1 gilles gilles 132718673 sept.  9 05:07 blk04488.dat
-rw-rw-r--  1 gilles gilles 133371822 sept.  9 06:18 blk04489.dat
-rw-rw-r--  1 gilles gilles  50331648 sept.  9 05:19 blk04490.dat
drwxrwxr-x  2 gilles gilles      4096 sept.  9 06:30 index
drwxrwxr-x  3 gilles gilles      4096 nov.  18  2023 regtest
-rw-rw-r--  1 gilles gilles  17758669 sept.  9 01:33 rev04478.dat
-rw-rw-r--  1 gilles gilles  16494748 sept.  9 01:53 rev04479.dat
-rw-rw-r--  1 gilles gilles  16785371 sept.  9 02:31 rev04480.dat
-rw-rw-r--  1 gilles gilles  19840678 sept.  9 02:32 rev04481.dat
-rw-rw-r--  1 gilles gilles  20110498 sept.  9 02:39 rev04482.dat
-rw-rw-r--  1 gilles gilles  20760162 sept.  9 02:53 rev04483.dat
-rw-rw-r--  1 gilles gilles  19349989 sept.  9 03:11 rev04484.dat
-rw-rw-r--  1 gilles gilles  20636297 sept.  9 03:42 rev04485.dat
-rw-rw-r--  1 gilles gilles  20220572 sept.  9 03:51 rev04486.dat
-rw-rw-r--  1 gilles gilles  21583482 sept.  9 05:02 rev04487.dat
-rw-rw-r--  1 gilles gilles  20858529 sept.  9 05:10 rev04488.dat
-rw-rw-r--  1 gilles gilles  20971520 sept.  9 06:18 rev04489.dat
-rw-rw-r--  1 gilles gilles   2097152 sept.  9 05:19 rev04490.dat

Please help me.

[nc50lc]

Can you tell me how to build a file settings.json which i could put my wallets secured too?

It's just in simple json format.
For wallet, simply type your wallet file names exactly like this (except the exact wallet's name);
For one wallet:

Code:

{
    "wallet": [
        "wallet name 1"
    ]
}

For two or more wallets:

Code:

{
    "wallet": [
        "wallet name 1",
        "wallet name 2"
    ]
}

The gist is, if there's two or more wallets, put a "," sign after the wallet name, if it's the last/single wallet, do not include a ",".
The "wallet name" are the folders you can find inside "wallets" directory, add the quotation marks as shown in the examples.

Somebody on the internet told us to just copy the backup but it doesn't work, each time i launched Bitcoin core it erase all the data.

That'll work assuming that every setting is set correctly and chainstate & blocks folders are intact.

I assume that when you try to load the wallet files which are auto-unloaded by the blank "settings.json" file, your pruned node asked for --reindex which triggers the IBD.
Also, you might have set some incompatible settings in the GUI before, that you haven't set in the new install, specially: "Prune block storage" settings.
If so, you can re-initialize Bitcoin Core with: $ bitcoin-qt --choosedatadir set your previous settings and point it to your data directory.
Alternatively, set your previous settings to your bitcoin.conf file.

[ujiko]

Well i had to restart a new blockchain, but curiously when 2024arrive, the ratio of downloading fail under 0.02% per hour if i do nothing, moreover i was frequently shut down of the core.
So this is a tip : select your peers, it's very very important, you must disconnect who lock your downloading process and maybe nukers.
https://www.haku.fr/nodes.png

[nc50lc]

Well i had to restart a new blockchain, but curiously when 2024arrive, the ratio of downloading fail under 0.02% per hour if i do nothing, moreover i was frequently shut down of the core.

I'm pretty sure this is just due to your Hard Drive being the bottleneck and that estimate is always way inaccurate if the datadir is in a slow hard drive and with low dbcache.
Of course, getting bad peers can be an issue too but seeing those "ping" values, most of them should be sufficient and fast enough to download the blockchain.
It's just your node is struggling with all the processes including the script verifications that's skipped in the older blocks,
as well as your settings (if you're using the default) and the slow hard drive.

Since you've started IBD (Initial Block Download) instead, let's just assume that this thread's issue is now solved.

[LoyceV]

So this is a tip : select your peers, it's very very important, you must disconnect who lock your downloading process

I've never had to manually block peers. It normally works fine on it's own.

Well i had to restart a new blockchain, but curiously when 2024arrive, the ratio of downloading fail under 0.02% per hour

I'm pretty sure this is just due to your Hard Drive being the bottleneck

Agreed. In 2024, Ordinal spam caused chainstate to grow fast. If you don't have enough RAM and use an SSD, this is going to be very slow. I (still) have my blocks directory on HDD, but chainstate has been on SSD for years. That makes a huge difference in download speed, while it doesn't take too much space on your SSD.
If you don't have an SSD: buy one