Question
Eudoro van der Biest · Apr 23, 2021

Log (Journal) shipping

I am new to Cache, we are trying to move a 4 TB database over the internet, but this will be take too long to copy the single backup file. In Oracle and MS-SQL Server there is an option of doing log shipping. Is there such an option in Cache?

I want to copy the initial backup file one weekend, then keep sending the Journals (logs) the new location.

Thank you,

Eudoro

Product version: IRIS 2020.2
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Replies

Hello Eudoro,

It sounds like you may be able to leverage mirroring, which is built-in and is an IRIS functionality where separate instances of IRIS can automatically transfer journal files to synchronize their copies of a database. Docs here:

Mirroring Architecture and Planning

Mirroring is also available in Caché

Just my 2 cent suggestion, CACHE.DAT and IRIS.DAT can be (usually) well compressed, the catchwords are winzip and winrar (I prefer winrar over winzip). Winrar, despite the word "win" in name, is also available for linux.


An example: winzip turned a 16GB CACHE.DAT into 3.45GB,  winrar (mode=best) topped this with 2.2GB, but as always, your values will depend on your data. And mind the time you need to compress and decompress the files, which, of course will depend on your hardware...

For example (command line)

rar a -m4 -m512 -v4g <pathTo>cachetransfer <pathTo>cache.dat

will create as many compressed files as needed, each (but the last one) with a size of 4GB, with good compression using dictionary of 512KB size.

You will get, in total, roughly 250 (*.rar) files (each with size of 4GB), I assume, 4TB compresses to 1TB.
When the first 4GB (rar)file is ready, start the transfer in parallel (one job does the compression and the other(s) work(s) on transfer - maybe you have multiple internet connections). Further, suppose you have a continuous (internet) connection between your and the target system with 100 Mbps then, again roughly, the job is done in 28 hours... better then transferring 4TB in a week or more (it's easier to restart a 4GB file as a 4TB file)

RAR is proprietary format, I would recommend 7zip, which works even better, and for free

nothing against 7zip, merely, I use (win)rar since the mid-nineties. And as you probably know, old habits never die...