hi all, i'm managing a large installation of a dovecot cluster in director + NFS backend architecture and we are moving from NFSv3 to NFSv4. Our NFS server is a Netapp in clustered mode and reading technical specs of NFSv4 delegation feature it seems that enabling delegation in this type of dovecot architecture should bring great benefits: only one backend server access a specific mailbox at a time (even deliveries are managed by director hashing via LMTP) so the getattr rpc calls should decrease significantly while the risk of conflicting delegations is very low (impacting negatively on the benefits obtainable). Can anyone confirm this hypothesis? I've heard that the linux implementation of NFSv4 delegation is mature only for read delegation (and not yet for write delegation): is this true? And, if true, could this fact limit the benefits of activating NFS delegation feature? Best regards -brd
Il 11/06/2015 16:03, brd ha scritto:> hi all, > i'm managing a large installation of a dovecot cluster in director + NFS > backend architecture and we are moving from NFSv3 to NFSv4. Our NFS > server is a NetappHi, I'm running a similar configuration, expect for the size (medium), with Dovecot/Director and NetApp (but without clustered mode), mailbox are in Maildir format. Have you already try to run NFSv4? When we switch to netapp and nfsv4 we had many problems (lock problems and instability) and we had to go immediately to NFSv3. I don't know if was a netapp problem or nfs client (Debian with 2.6 kernel), now we are using Centos 6 as NFS client and we should re-try to mount mailbox as nfsv4. Let me know if nfsv4 works fine for you. Ciao -- Alessio Cecchi http://www.linkedin.com/in/alessice
Alessio Cecchi wrote: [...]> Have you already try to run NFSv4?it's in place on a (very) small sample of mailboxes in dbox format, no issues up to now (Debian Wheezy mainline kernel)> When we switch to netapp and nfsv4 we had many problems (lock problems > and instability) and we had to go immediately to NFSv3. I don't know if > was a netapp problem or nfs client (Debian with 2.6 kernel), now we are > using Centos 6 as NFS client and we should re-try to mount mailbox as nfsv4.when you've had problems, the "delegation feature" was active on Netapp filers? (AFAIK it is disabled by default) you had a look here for known bugs? https://kb.netapp.com/support/index?id=3014338&page=content ciao -brd