On 2019-12-04, venbian via Exim-users <[email protected]> wrote: > Hello gurus, > > As 2020 nears I wanted to ask opinions about the current state of > hardware requirements for a small business email platform. $dayjob > asked me to enhance our existing platform to improve performance and > add redundancy.
Q1: how much of each? > Main questions (TLDR): > > Can NFS handle heavy IMAP, LDA, HTTP workload? yes: this is not microsoft - there are no software performance limits. But using NFS for server disk will double your network traffic (or worse when doing server side searches) > Is direct attached SATA III 6Gb/s SSD in RAID 1 sufficient or is SAS needed? see Q1 > Is gigabit ethernet the bottleneck in any case? I can upgrade to a > 10 gigabit local network if advisable. > Can NFS peacefully co-exist with other mail system workloads without > resource contention such as SQL DB or spamassassin or redis, etc? if your database is on direct attached disk then yes. > More detail: > > I had bad experiences with NFS approx 15yrs ago where IMAP load > saturated controller link (yes, noatime was used on the mount) and was > unusable. But in 2020 is it time to give NFS another look? why would you want to use NFS? I would pick E-SATA or USB3 direct-attach over NFS, and internal direct-attach over that. > Current mail storage setup uses local attached large SATA SSD and >does well, but it directly hosts HTTP, LDA, IMAP and Submission which >could all be faster and it only does nightly backups. Adding SAN is >probably out of $dayjob pricerange and SAS is borderline. Power >consumption is also a factor so instead of a dedicated file server I >thought it would make more sense to build a big server with direct >attached fast SATA SSD in mirrored RAID that also has strong CPU and >maximum memory so it can also run some of the backend process such as >spamassassin, redis or SQL database etc. (we want to start using SQL >DB for more which means it will be under heavy use) > What workloads can best co-exist with NFS where each does not contend for the > other's resources? NFS server uses disk and LAN, D L NFS client uses RAM and LAN, R L S.A. uses CPU and RAM, R C Redis uses RAM and CPU R C SQL uses RAM and disk and CPU D R C Redis and SQL also use the lan if they're serving other servers. > I'd put a couple smaller machines in HA in front of that to proxy > webmail, HTTP website, IMAP and Submission. Edge MTA is on a separate > server and would probably stay that way, maybe adding a failover. It > keeps a fraction of its mail in the local system but will make more > heavy use of the SQL DB which I thought to also put on the file > server(?) > Could NFS keep up with load for proxy of HTTP, IMAP, LDA, etc? > > Is local attached SATA SSD in RAID 1 ok? Will 6Gb/s SATA III be a bottleneck > in any possible scenario? I was looking at motherboards with multiple PCIe or > M.2 slots thinking NVMe bandwidth (3GB/s) would be great but I'm unsure if > NFS, gigabit ethernet or other components could even make use of it. see Q1 > Or is that too amateur and local attached (hope not remote attached) SAS a > minimum requirement? SAS SSDs are a newer thing I never used and expensive > for the $boss. I read some people express doubts that SSD is suited for SAS > at all which is one reason I thought just use SATA for more efficient power > and cost. > > Our workload: > > We process a lot of mail but as you can guess, don't have tremendous > storage needs. We have several tens of thousands of users but a > smaller fraction of that are actively using mail every day. Maildir > storage is several TB. Exact daily mail volume is unknown but should > be on the order of a few million, many which users have forwarded to > to other accounts so a small fraction is stored locally. Forwarding can get messy when gmail thinks _you_ are spamming. SATA will probably work alright there. > We also have few TB of web data that is hosted from a server in the > same location that I thought to unify into the NFS setup. I wouldn't use NFS as server disk unless the service was CPU intensive. so servers running Redis or S.A. are good candidates for being NFS clients. others not so much. -- When I tried casting out nines I made a hash of it. -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
