Group share woes

Update 20.12.: the strange intermittent permission problems some of you experienced could be traced back to a kernel regression. We’re now back to using an older kernel.

Update 13.12.: we’re cautiously optimistic that the problems have been fixed. Since Monday the file server has survived everything we threw at it. The culprit seems to be an Infiniband switch that sporadically disconnected under heavy load. We’re now also turning on some performance improvements again, so you should see a speed increase when browsing files.

Update 06:45: group shares are back. Please let us know if you encounter any problems.

As some of you might have noticed, we’ve had some service quality issues with our group share server in the last few months. While not all interruptions are under our control (Informatikdienste lately have been very busy upgrading the ETH network, causing various network disruptions), we do have a problem with the group share server: it runs fine for weeks on end until it suddenly doesn’t. To this day we have not been able to pinpoint the underlying problem, despite having changed a lot of parameters, both software and hardware. Our next step will be replacing the kernel on the disk backends and switch some hardware – for that we need a scheduled downtime on

Monday, December 11, starting at 06:00

during which the group shares will be unavailable for about 90 minutes. This affects all D-PHYS and IGP shares except the Astro and newly migrated IPA ones. We will post an update when the system is back.

We do apologize for the inconvenience these service issues might have caused you. Please bear with us while we’re trying to locate and eliminate the root cause. We’re monitoring the situation 24/7 and try to react as quickly as possible whenever a problem occurs. But wait! You can help! There seems to be a correlation between crash probability and large scale small file I/O. This means you should, whenever possible, avoid reading or writing a lot of small files and bundle your data into fewer and larger files. This also increases performance!

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