A2 is running Linux per their site.
One possible problem that you are running out of free space or inodes (the latter is roughly equivalent to the total number of files and directories). You need enough space for the backup archive, the extracted files and the database data.
The other possible problem is that they have a request rate limit. On Apache they are usually implemented with mod_evasive (no longer maintained), mod_security2 or mod_qos. They reject requests if they are coming “too fast”. On the database side you can set up MySQL or MariaDB to limit the maximum number of requests in a given amount of time.
I assume that you have a problem extracting the archive which would be the former rate limit — on the web server. You can try to work around these limits with the min/max settings. I'd use super conservative settings: maximum execution time 3 seconds, minimum execution time 8 seconds. This limits the requests to 7 requests per minute and is dead slow. If even that does not work, ugh, I mean you CAN extract the backup archive locally and upload all the files, then access /installation/index.php on the live server after having uploaded all the files.
Still, you'd probably have a hard time restoring the database because of the request rate limit and/or database query rate limits.
Another issue you may have — I do not know if they actually implement something like that — is file scanning on creation. Joomla and its extensions contain many file which may be misidentified as malicious by a naive file scanner. We've seen some hosts which automatically kill PHP scripts or delete fails if the file scanner misfires.
None of these issues are, of course, issues with our software. They are server configuration issues and can prevent you from restoring your backup archive.
Start with the min/max settings to rate limit the requests. If it still fails, check the free space. If there's enough free space contact the host and say, hey, you are clearly rate limiting requests, how am I supposed to restore AN ENTIRE SITE if you don't let me run the script which extracts the files and runs the database queries to populate the database? The first level of support will be useless (they have no authority, they are just there to tackle the easy support requests), so don't be afraid to escalate to second or third support tier.
Nicholas K. Dionysopoulos
Lead Developer and Director
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