How to optimize UrBackup advanced settings


I have some dudes about the most recommended configuration of transfer modes in advanced settings of server, and how this is impacted in clients (in terms of speed and reliability), and also which is the dependency of the type of client (CBT or not) with this settings.
Can anybody put some light on this?

The transfer modes are:

  • Hashed
  • Raw
  • Block differences - Hashed

I have readed the documentation, but it is not very explicit on this.

Thank you so much.

When in doubt, accept the defaults, while there are good reasons in different situations to choose any, hence being given the choice, the defaults are the most common choice because the devs thought about it, not because they tossed a coin.

Without knowing your setup in detail, nobody can be much more helpful than that.

I have some different scenarios using UrBackup, some installed directly on NAS, some in computers, with different type of clients, CBT and standard… so, my question is not about a specific configuration, it is about the behaviour of every different setting and how it affects on different situations.

Does this help?

8.5.2 Transfer modes

UrBackup has different transfer modes for files and images. Those are:

  • raw. Transfer the data as ’raw’ as possible. This is the fastest transfer mode and uses the least amount of CPU cycles on server and client.
  • hashed. Protects the transferred data from bit errors by hashing the data during the transfer. This uses CPU cycles on the client and the server.
    UrBackup uses TCP/IP to transfer the images and files. TCP/IP implements its own bit error detection mechanism (CRC32). If the network induces a lot of bit errors and if a lot of data is transferred (>2TB), however, the bit error detection mechanism of TCP/IP is not enough to detect all occurring errors. The ’hashed’ transfer mode adds an additional layer of protection to make bit errors less probable. You do not need to use the hashed transfer mode if you backup via a Internet mode connection with enabled encryption, as the encryption layer already protects the integrity of the transmitted data.
  • Block differences - hashed. Only available for file backups (as it is automatically done for images). Blocks of the transferred files are compared using CRC32 and MD5 hash functions. Only blocks which have changed are sent over the network. In cases where only some blocks of a file change, this reduces the amount of transferred data. It also causes more messages to be sent between server and client and uses CPU cycles, which is why it is only enabled for Internet clients per default.

I readed the documentation, but what I miss is how affects these settings if the client is CBT, or normal client. Are different recommended settings depending of the type of clients.?

Roberto López - NESIC/Eurosistemas
(Enviado desde mi dispositivo móvil)

Yeah, file CBT only works if using Block differences - hashed


That is what I supposed reading the description of the characteristic, and in all of my clients which have CBT I configured it this way… but, if it isn´t documented is difficult to know if is a correct configuration.

I suggest that could be necessary include this info when you purchase CBT.


CBT massive improves backup speed. E.g backing up an Exchange-Server 2016 with ~1TB database reduces incremental backup time from 9h to 1,5h on a deduped ZFS storage without TMPDIR set. And yes, I think so too: The docs has to be updated to make this clear.