From mboxrd@z Thu Jan 1 00:00:00 1970 From: Phillip Susi Subject: Re: Packed small files Date: Fri, 10 Feb 2012 14:02:26 -0500 Message-ID: <4F3569C2.7090809@ubuntu.com> References: <20120131164610.GE5531@carfax.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 To: Hugo Mills , Hans Stimer , linux-btrfs Return-path: In-Reply-To: <20120131164610.GE5531@carfax.org.uk> List-ID: -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 1/31/2012 11:46 AM, Hugo Mills wrote: > So you're looking at a minimum of 413 bytes of metadata overhead > for an inline file, plus the length of the filename. > > Also note that the file is stored in the metadata, so by default > it's stored with DUP or RAID-1 replication (even if data is set to > be "single"). This means that you'll actually use up twice this > amount of space on the disks, unless you create the FS with > metadata set to "single". > > I don't know how these figures compare with other filesystems. My > entirely uneducated guess is that they're probably comparable, > with the exception of the DUP effect. On ext4 you are looking at 256 bytes for the inode, name length + a few bytes for the directory entry, another few bytes for the hashed directory entry, and a whole 4k block to hold the data, so ~4300 bytes ( + name length ) of overhead to store a 64 byte file. -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.17 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEcBAEBAgAGBQJPNWnBAAoJEJrBOlT6nu75lVkIAIO2mjYeVK5BbMNfw5HJ7jZO WfIBv5xR8V06e0VLgv4FQqPlWcm+ZQHorYDM7h15q4cIgoZ3x0P3n3bSCurFRLfF lSRjn/fsX1Y9isPEB6/monPm+08U6qh7jXGldEMOLKaA7VG/QOVR01k3W2a3FkJ4 kWBjEbK/xE013WaQnfR26PydRT8ILRzGUE4uEKGsdV39JkcEorQ1lDg+XWz5Hvy7 VmelT21272PssIUbRub1QkZXj6p0SUu1zeU1IwOdt6X1uXFcWqFbBFRGJk4f2+ZM 5MquuVC+YrzfDIBnS0ZBZ4UqNmxYuPCSzTLlpPiJJiY/AwR7916H/CoF5k38k/M= =8YmX -----END PGP SIGNATURE-----