The storage fills up, and every extra terabyte costs money every month. At the same time, the admin wants to restore, move or delete one account without touching the others. How much space is lost by storing each account in its own repository, without sharing repeated files between accounts, and how much does compression win back?
Why it matters to whoever runs the server
- Half the space: with compression, the backup of 12 accounts went from 5.93 GB to 2.94 GB. The same storage holds twice the backup.
- Independence has a price, and we measured it: keeping each account separate costs 28% more. The default keeps independence; whoever prefers space picks a single repository or one per group of accounts.
See the data as a table
| Compression | Single repository | One per account |
|---|---|---|
| None | 4.28 GB | 5.93 GB |
| zstd-fastest | 2.30 GB | 2.94 GB |
| zstd | 2.26 GB | 2.87 GB |
Method
A production cPanel server (AlmaLinux 8, 8 cores, 11 GB of memory). Sample of 12 mid-sized WordPress accounts: 6.11 GB and 226 thousand files.
The source was only read, one account at a time, at low priority, with a 1 GB memory cap for the test and an automatic pause if load went over the limit.
Salvo engine, writing over SFTP to a ZFS storage, with encrypted data. Default zstd saved only ~2% more than zstd-fastest (1.7–2.4%) and, in the single repository, used up to 40% more memory (797 vs 572 MB).
What we decided
The administrator chooses, per destination: one repository per account (default), a single one, or one per group of accounts; and zstd-fastest (default), zstd or no compression. The default favors independence between accounts (restoring, moving or deleting one never touches the others) and the lighter compression.