Scalability of Dovecot in the Cloud

[Marc Stürmer]

Zitat von KT Walrus <kevin at my.walr.us>:

> Does anyone have any idea of how many IMAP connections a single  
> cloud VM (4 vCores at 2.4GHz, 30GB RAM, local SSD storage -  
> non-RAID) can be expected to handle in production. The mailboxes are  
> fairly small (average 5MB total - 50MB max, as I don’t store  
> attachments in Dovecot expect those saved through IMAP in the  
> Sent/Drafts folders) and each user will probably have an average of  
> 2 devices that have the mail clients configured to access each  
> mailbox.
>
> Can such a server handle 100,000 mailboxes (200,000  
> devices/clients)? Or is it more like 10,000? Or, even smaller?

The bottleneck of IMAP-operations normally is the number of needed  
IOPS for accessing the mail storage, which depends on the mean number  
of concurrent users to be expected.

Can such a server handle this number of mailboxes? Most certainly yes.  
The real question is: can such a server cope up with the expected load  
of concurrent user sessions you are expecting?