From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Ingo_Gl=F6ckner?= Subject: Questions regarding use of nilfs2 on SSDs Date: Sat, 28 Mar 2009 21:55:54 +0100 Message-ID: <49CE8EDA.8070304@web.de> Reply-To: NILFS Users mailing list Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: users-bounces-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org Errors-To: users-bounces-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org To: users-JrjvKiOkagjYtjvyW6yDsg@public.gmane.org Hello, first of all thank you very much for contributing this great file system, nilfs2! I would like to use nilfs2 on an SSD but there are some open questions, hopefully you can help me clearing these issues. - I have read somewhere > http://www.ocztechnologyforum.com/forum/showpost.php?p=3D361424&postcount= =3D10 that using nilfs2 as the rootfs generates enormous I/O traffic (up to 45 GB write in 1-2 days!) If this is true, then it will eventually translate into reduced lifetime for SSDs. Can you confirm that the segment management of nilfs2 is so write-heavy on the drive? If so, are there ways to avoid this? - The standard segment size of nilfs2 appears to be 8MB. This compares to an erase block size of the SSD of (say) 512 KB. I wonder if reducing the segment size of nilfs to a smaller value (i.e., closer to the erase block size of the SSD) will help to keep the number of erased blocks/day small (this will benefit the lifetime of the drive) or if there is no such connection. In any case, what is the useful range for segment sizes? If I reduce the segment size, will I get a performance penalty? - nilfs_cleanerd.conf specifies the following default values, # The maximum number of segments to be cleaned at a time. nsegments_per_clean 2 # Cleaning interval in second. cleaning_interval 5 Do I interpret this correctly as stating that only 2 segments (i.e. 16MB) can be cleaned in 5 seconds? What negative effects will I get if I increase the number of segments that can be cleaned at a time? Thanks in advance for your help! Cheers, Ingo Gl=F6ckner