On 10/17/2015 02:08 AM, Dan Egli wrote: > Okay, I will just ask this part, and then I think I've gotten all the info > I need, thanks. You mentioned changing the size of your extent on your > Dual-Tuner MythTV box. What's the default extent size, and given the usage > I mentioned (10-20% executable & data - which is where I was thinking of > Data Dedup, 80-90% multi-media), would that be sufficent for my needs, do > you think? If not, what would be a good extent size? Given the average size > of some of the files I will be handling, I'm ALMOST tempted to make an > extent size of 90MB, but that would be space wasting for the binary > programs and such.
Hopefully Daniel can speak to his XFS settings. I'm curious about that myself as my reading of the XFS docs suggests that the only influence you have with extents on XFS is on something called a real-time partition, which I don't fully understand, but which seems to be a special case. As far as I know with Ext4, it's all just automatic, so there's nothing you have to change. There are certainly no mkfs.ext4 options for it that I'm aware of, except to disable the feature entirely. My advice is not to worry about extent size. > Also, as just occured to me, speaking of extents. If I make, just say a > 60MB extent, then write, say, 10 files that are 2MB ea when complete, > that's 20 MB. Is XFS going to put all ten of those in one extent, or would > I have 600MB allocated but only 20MB used? Just wondering. As far as I know an extent is only a reservation, for use in case a file grows, thus keeping it contiguous in that event. Eventually storage pressure will cause that reservation to be lost. The smallest unit of storage is still going to be your block size, but even there Ext4 can store very small files in the inode itself, so some of that internal fragmentation can be avoided. /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
