<div>On 10/4/05, Arjan van de Ven <<a href="mailto:arjanv@redhat.com">arjanv@redhat.com</a>> wrote:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> On Tue, 2005-10-04 at 12:24 -0500, Justin Conover wrote: > tune2fs > -m reserved-blocks-percentage > -r reserved-blocks-count > > If what I have read is correct, -m by default uses 5% of the disk > space for "reserved root use" On my server at home with a /home of > 1TB thats about 50GB of wasted space. > > Is this reserved space actually used by ANYTHING? Like LVM, some kind > of fragmentation? well for emergency root stuff; logging in without any disk space is hard; lots of stuff wants to make temporary files etc. but your second point it true too: most filesystems (ext3 but most others) start to fragment like hell if they go over about 95% full. Think of it this way: if you have half your disk empty, the filesystem can do a proper job of finding non-fragmented space. If only 0.0001% is free, it has almost no freedom of choice, resulting in "you get it in whatever order some things become free". Those are sort of extremes; there's been a bunch of research and the outcome was that 5% free seems to be sort of the turning point in this respect. I suspect that research predates the Tb sized volumes, so I don't know if it maybe is 1% on such volumes, but then again to some extend the freedom needed will scale with the FS size -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) iD8DBQBDQsEXpv2rCoFn+CIRAvUXAJ0SH+Pc9eXpinhuBGZ+DM4r5wTCtgCgi+7B hxT89EtumMwOF13z0l0KP9Q= =C5z1 -----END PGP SIGNATURE----- </blockquote></div>So, lets say you have a production server with a 20GB filesystem used for a Oracle Database, would lowering it to 1-2% be safe or should you leave this at default. FYI, I'm not asking for support, just curious were the line is on importance. You start getting in to 200GB-1TB file systems then you have a pretty large area of un-allocated space.