1. CPU Architecture: LISTSERV runs under 64-bit Windows on 64-bit Intel architectures only.
    2. Multiple Processors: While LISTSERV itself will not use multiple processors (LISTSERV is a single-threaded application), overall machine performance may be enhanced by use of multiple processors if other applications running simultaneously on the machine can take advantage of them.
    3. Memory: L-Soft recommends that a dedicated Windows LISTSERV machine start out with a minimum of 8GB, as this will minimize paging and can lead to a marked improvement in performance, particularly if the web archive/administration interface (see below) is implemented.  In particular, LISTSERV servers running with the High Performance Option (HPO) require more memory than non-HPO servers and should therefore start out with at least 16GB.
    4. Disk Space Needed: LISTSERV itself takes up very little space (perhaps 4MB total for all of its default system files). When planning a LISTSERV system you need to take into account how large your lists will be (100 bytes per subscriber entry in a given list) and how much space you will need for discussion list archives, which have the potential to grow quite large depending on your traffic and number of lists.  For most small systems, a 4GB or larger drive is probably sufficient for some time.  Larger systems will naturally require larger disks.

Important: Disk space needed will potentially be greater than expected if LISTSERV's Mail-Merge functionality is enabled for a list and a very large attachment is posted to the list.  If a list is configured with 'Mail-Merge= Yes', LISTSERV will create a separate .mail file in listserv\spool\ containing a copy of the message for each recipient when a mailing is sent to this list.  Therefore, at minimum you will need enough free disk space to accommodate the total volume of those .mail files. A rough estimate of the space required for such messages is the size of the message (including attachments) multiplied by the number of recipients. However, encoding the attachments requires a certain amount of additional overhead space.  Therefore it is best to ensure that the available free disk space exceeds that rule of thumb by a good margin, particularly if there is a possibility that multiple large mailings will go out in close succession.
    1. Disk Architecture: LISTSERV will run perfectly well for most sites on inexpensive SATA disks of the modern sort. If performance is an issue, it will be greatly enhanced by the use of fast SAS disks in a RAID array with write-back caching and a write-back battery back-up. Write-through caching is not recommended.  Usually it is best to divide a RAID array into at least two partitions: A boot partition of 3GB (effective 1.5GB) RAID 0+1, and a data partition making up the rest of the available disk space at RAID 5.  If it is not feasible to divide the array in this manner, RAID 0+1 for the entire array is suggested.  (The boot partition can be larger if desired -- particularly as very large disks are much more economical than in the past -- but we would still recommend that it be configured RAID 0+1).

With prices continuing to drop for modern data storage, the above should be considered absolute minimums and we would actually recommend starting with larger disks and partitions wherever possible.

With regard to solid state drives (SSD), we consider it prudent to caution against using SSD for highly-dynamic data such as LISTSERV's spool and archives.  SSD might profitably be used for boot partitions, however, where data (at least in comparison to LISTSERV's data) rarely or only occasionally changes.

    1. Disk Format and Security: L-Soft strongly recommends that LISTSERV be installed on an NTFS-formatted partition. LISTSERV will run out of a FAT (or FAT32) partition, but FAT does not provide the same level of security and performance available with NTFS.
    2. LISTSERV in a virtualized environment: LISTSERV works very well in a Microsoft Hyper-V environment.  We recommend using a dedicated Hyper-V instance for this purpose, with service parameters adjusted to fit your local needs.  The same minimums noted above for physical servers apply to Hyper-V instances.  If you are looking for a high-availability solution for LISTSERV for Windows, Hyper-V with its failover clustering feature may be what you are looking for.

      Customers have also reported success running LISTSERV in virtual environments such as Microsoft Azure.  L-Soft's own ListPlex hosting service now runs almost entirely on Microsoft Azure.

General performance notes:

      • L-Soft STRONGLY DISCOURAGES running LISTSERV out of a RAM disk in order to speed up I/O.  This is not a supported configuration and if you have problems with it the support group's response will be to tell you to stop using the RAM disk.
      • If system RAM is tight, either a fast disk or more RAM is a necessity if you are to minimize I/O time lost to paging.  An otherwise fast system can become quite sluggish if it is required constantly to read and write to virtual memory. Adding more RAM is usually preferred as it is more efficient to access RAM than it is to access even a fast disk.