Hosting: sizing#
This documentation applies to Piler enterprise edition 2.2.5+
Revision #1
Publication date: 2026-OCT-25
How much storage a tenant needs, and how many tenants a server holds. The figures come from large deployments: sizing.
Per tenant#
emails per year = users × emails per user per day × 365
stored emails = emails × average size × 30-40% (deduplicated, compressed)
index + database = ~2.8 GB per million emails (Manticore ~1 GB, MariaDB ~1.8 GB)
Hosted mailboxes are usually less active than corporate ones. With 30 emails per user a day and 75 kB per email, one year of archive is:
| Tenant | Emails per year | Stored emails (S3 or disk) | Index + database (SSD) |
|---|---|---|---|
| 50 users | 0.55 million | 12-16 GB | 1.5 GB |
| 500 users | 5.5 million | 120-165 GB | 15 GB |
| 5,000 users | 55 million | 1.2-1.6 TB | 150 GB |
Multiply by the years of retention. A tenant's archive grows until its retention starts purging, so plan for the full retention period.
Tenants per server#
The stored emails go to object storage (or a large, cheap volume); what fills a worker is the index and the database on fast storage, and the memory that keeps searches fast. So a worker holds tenants until:
- their index and database fill its SSD, e.g. a 1 TB SSD holds the index and database of about 350 million emails, the archive of sixty 500-user tenants for a year; and
- searches stay fast: the Manticore index and the MariaDB buffer pool are served best from memory. Add memory before adding workers.
Many small tenants fit a single node, starting from the minimum of 2 vCPUs, 2 GB of memory and 200 GB of disk (see the overview). Large tenants and a high email rate call for workers: add one when a worker's disk, memory or CPU runs out, and new email is spread among them (see architecture). A proof of concept with a sample of your email traffic confirms the numbers.
The math for your offer#
The license is per server, the same price for one tenant as for a hundred, so your cost per tenant falls with every tenant on a server:
cost per tenant = (licenses + servers + storage) / tenants
The storage is the part that grows with each tenant's archive: price your offer by the stored size, which the usage reports give you per tenant.
Use the email archive sizing calculator for your own volume.