Freminlins <[EMAIL PROTECTED]> writes: > Gayn Winters wrote: > > > What I get from reading this article is that if the use of the file > > system is to store lots of small files, then use a small block size. Am > > I missing something? > > No and yes! There is a minimum block and fragment size. In this case > there were not enough contiguous fragments to enable an 8K file to be > created. Without checking I believe Solaris uses 8K blocks.
That's correct, and also note that Solaris does not offer the flexibility in block sizes that is available from FreeBSD. And it is correct that a small block size will vastly reduce the ability to hit this fully-fragmented condition. At a cost of higher overhead, of course. > > Also, in most situations, buying a big enough disk is far better than > > worrying about what happens when a not-big-enough disk starts to get > > full. > > Indeed. But... in the case I linked to there was apparently plenty of > free space, just not enough free contiguous space. The author also > implies that a bigger disk would not solve the problem: > > "it creates and deletes tons of small files and thus the fragmentation > over a period of time." Where "plenty of free space" is a large absolute number, but still a small fraction of the disk. Full fragmentation of the empty space becomes exponentially less likely as the amount of free space increases. Note that when deciding where to allocate a fragment, there are two possible policies the filesystem can follow: either a space-efficient method that is more likely to require moving data when a file expands, or a time-efficient method that will create new fragments more often. FreeBSD can automatically shift between the two as the filesystem moves over or under a threshold "percent full" value. Solaris, I believe, needs to be explicitly changed between the two. > As mentioned though I have never seen this myself despite running very > busy mail and web servers with what must be billions of files being > created/deleted in that time. > > It certainly grabbed my attention so I thought it may be of interest to > others. It's an academic curiosity, but not an issue to take into account in planning your data center. Planning your filesystem layout, however, may well be. Be well. _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
