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It's convenient most of the time, but sometimes building your own stuff is inconvenient most of the time. It's all about trade-offs. For example, a while back
by pyre 11y ago
It's convenient most of the time, but sometimes building your own stuff is inconvenient most of the time. It's all about trade-offs.
For example, a while back I had to track down an issue on a server with Nagios constantly triggering memory low errors. Turns own that when you stat a lot of files, XFS will load all of that file information into cache in the kernel's slab. This causes some RAM stats to be skewed. This RAM will be instantly freed if needed, but some system stats count it towards "RAM usage."
My question is: How does one incorporate all such edge-cases into something that is user-friendly? How many system admins even know how to track down such an issue (in the absence of a flashy UI)?
Unless you want to vertically integrate the system from hardware => kernel => UI, then you're bound to have these sorts of issues where everyone is only paying attention with what's happening in their own little area of concern and multiple decoupled systems can end up interacting poorly (even when their local actions make sense to them).
- laumars 11y agoRe cached memory, isn't that how all file systems work across all the major operating systems? The kernel space will cache files to reduce disk IO but will immediately free that memory if a requesting application allocated more memory that's what's available in free memory alone. Which is why file servers perform best with ooodles of RAM and why one should always look at both the free + cached memory when calculating available memory on more general purpose systems. Or was your NAS behaving subtly different from the standard above? (eg how ZFS cache doesn't appear as FS cache in ZoL despite freeing in much the same way as the above)
- pyre 11y agoThis is a specific XFS behaviour. In this case, the slab was using up 4GB of RAM on a 8GB machine, and all of the normal tools were telling us that we were running out of free space in RAM. No such problems on other file systems.
- e40 11y agoWhat they offer is a good form factor with lower power. What would you suggest for a home brew, that would match size and power consumption?
- SirMaster 11y agoForm factor? A case like these: http://www.newegg.com/Product/Product.aspx?Item=N82E16811219048 http://www.newegg.com/Product/Product.aspx?Item=N82E16811219... http://www.newegg.com/Product/Product.aspx?Item=N82E16811219054 http://www.newegg.com/Product/Product.aspx?Item=N82E16811219... http://www.newegg.com/Product/Product.aspx?Item=N82E16811163255 http://www.newegg.com/Product/Product.aspx?Item=N82E16811163... http://www.u-nas.com/product/nsc800.html http://www.u-nas.com/product/nsc800.html Low power usage? Well many Synology units use Intel Atom CPUs. Anyone can buy a small board that has these same Intel Atom CPUs and stick them in those cases. Or make your server with NUC parts which use laptop CPUs. Like <15W parts. Even higher end CPUs these days idle at really low wattage. So your NAS when idling wont use much power.