From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Masover Subject: Re: Less disk space with reiser4? Date: Mon, 11 Apr 2005 19:57:12 -0500 Message-ID: <425B1CE8.3090904@slaphack.com> References: <425A8A1D.9040206@siwnet.net> <20050411195253.GD6211@backtop.namesys.com> <425ADC6C.8090209@namesys.com> <425AE170.7010806@nauticom.net> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: list-help: list-unsubscribe: list-post: Errors-To: flx@namesys.com In-Reply-To: <425AE170.7010806@nauticom.net> List-Id: Content-Type: text/plain; charset="us-ascii" To: "Chester R. Hosey" Cc: reiserfs-list@namesys.com -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Chester R. Hosey wrote: > Many filesystems claim degraded performance as free space decreases > beyond a certain threshold. However, they often allow the user to exceed > this point and accept the decline in performance. > > While Alex's explanation does well to explain why a certain amount of > free space is required in the case of a commit depending on a certain > amount of free space, it doesn't quite show that 45 gigs are required to > cover this requirement on a terabyte of space. Is this a reasonable > requirement? Not in my book. Let me second this. It's not all that expensive to build a terabyte array. It's much more expensive to build a box with 45 gigs of RAM. People who can afford to run Reiser4 on a box with 45 gigs of RAM can afford to hire you guys to patch it. I propose that the limit should be configurable, and modifiable online or offline with some sort of tunefs command. In fact, I propose that the default should be 5% or the total RAM at time of creation, whichever is lower. What if the user upgrades RAM? Change this value on mount, if the space is available, and create a mount option to override this behavior. Performance concerns should be addressed by printing a warning in dmesg, somewhat like "flushing like mad". And most filesystems suffer with more than 75% full, so it's better to educate the users than just steal a quarter of their space (or even a twentieth). -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iQIVAwUBQlsc6HgHNmZLgCUhAQK0Zw/+PLX+CFKx0xPHXBZiyhjykbLcOk1YBfJz tZ971xf3sE18hDbA3uEbuT6PkSvA5ihcICThk7wwUh9lM0HcN7epCmQqICRDBMl1 m5PJ/SlV4VEkbJEsevHmo1aFTY87c1WW9sk6gPWaHw10d7eGZqMMtuSXhHXOnJ3E 9/M4FZcJsUp/18Ur5e8SJvX5ach0LsYSnKL8vslv0uVaFCdr1lITGVLlztKh7j1n /UUQiwuGCT1WvOrPjySEUm7Y+eeC0eXea763ll90ZjuhVGsaSCsorIVSmuAm06YO VJC971hlkMOQJaYp7hduyiF8dskSHyQ4A76K+BArdo/tZdciRNlA/DAE3uG5GFKY xNxWit5fv4wm96f/X1A1rIPhxOyWK4teP2n9G/1UK+5+uYgLTUqtG8tGZ1WNDysz na5HgY2MwKXJQwlvLnABCDn4sFZV2amNd/r2//tcSZp6lM2gvXmoo4Velg4YMr2G TnnlLNf96LOoHQFdZvaDyeXxkFO8WaHbDSA7ffhXbYLkSfNpd8eY/ocGOO8YF9Jn mRmjecG4iveWg9y7I7DpQ5ofXEGVTYjH2d2Z+UnjN0D7mgm7x454rMgsjrLqHwL+ lsi116nLctIT63e3F9Eq3UQ/fI+QvfiyXXrDHec1oGBl3LFO8OuSGLsRr7GBbHfz kY4pgD+GIJU= =VhOT -----END PGP SIGNATURE-----