On 2020-01-07 14:06, Karel Gardas wrote: > > > On 1/7/20 7:38 PM, Jordan Geoghegan wrote: >> > Using softdep on /tmp is a silly idea. > > Why? To naive eyes it may look like a natural solution: e.g. before temp > file is even created (on drive), it may be deleted which means there is > no meta-data change hence speedup of operation on /tmp. In case of > classical ffs, you will need to create file (sync meta-data update), > save some data (async), delete file (sync meta-data update). But > honestly still need to read the code... >
I'm not going to go nearly as far as to say it's a silly idea (as I do it myself) but ... be aware softdep is funky. Weird stuff happens when Softdeps are working as designed. When you do things out of order, things happen...well, out of order. So ... create file delete file create file delete file create file delete file create file delete file create file delete file sounds perfectly safe, as long as "file" is smaller than available disk space, right? Softdeps...no so much. This can actually result in running out of disk space, as the deletes may not happen until after the creates. Another place where softdeps will sometimes bite you is when you unpack tar balls that overwrite existing files -- simple thought process says, "as long as you have enough space to cover the growth, fine". Softdeps might surprise you. You may get an "out of disk space" error, and a minute later, see much more space than you thought you could ever need to accomplish the task, once the deletions have time to take effect. So ... make sure you have lots of extra disk space...if things are snug, it's a bad place to use softdeps. Nick.
