According to Peter Ludikovsky in the debian-user list: ------------------------------------------------------------------------ Am 25.09.2015 um 14:04 schrieb Vincent Lefevre: > On 2015-09-25 10:11:10 +0200, Peter Ludikovsky wrote: >> My guess is: Due to the rather large wsize/rsize, the clients >> create a rather large attribute cache. As a result, when you cat >> a file on the second machine it updates the atime in the cache, >> but doesn't yet transfer that information to the server. When you >> do the mv on the first machine, the client tries to get the >> current attributes on the files involved, which prompts the >> server to wait until the second client runs into some kind of >> timeout and updates the attributes. Only then is the second file >> "unlocked" to be overwritten. >> >> Further proof of that: when setting noatime as a mount option, >> instead of noac, there's also no delay on the mv. > > Thanks for the explanations. But the second client, though it > doesn't update the attributes immediately, seems to do it quickly > when asked by the server, otherwise the problem would also be > visible on Debian 7 machines. I think that on Debian 8, when the > rename cannot be done immediately, the client retries after 15 > seconds instead of retrying earlier. > > Is this related to the following patch? > > http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8478eaa16e701ecfe054b62ec764bc1291b79e19
Can't say if it's related. I have, however, managed to capture the related network traffic (see attachments). The big difference happens at packets 58/54 (Deb7/Deb8). For Deb7, the RENAME call is immediately answered by an NFS4_OK, whereas for Deb8 as the client it's an NFS4ERR_DELAY. I haven't seen any reason on the client communication that would explain that, however this is far beyond my knowledge of the NFS internals. ------------------------------------------------------------------------ See https://lists.debian.org/debian-user/2015/09/msg01120.html for his message and the attachments. -- Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
