From: Masato Minda Subject: Re: How many files to create in one directory? Date: Tue, 28 Jan 2014 11:53:08 +0900 Message-ID: <52E71B94.4000406@jprs.co.jp> References: <52E607B1.2060206@jprs.co.jp> <52E69F3F.2000104@redhat.com> <20140127193950.GA20411@thunk.org> <52E6B80D.7060807@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: linux-ext4@vger.kernel.org To: Eric Sandeen , "Theodore Ts'o" Return-path: Received: from off-send01.tyo.jprs.co.jp ([202.11.16.150]:54457 "EHLO off-send01.tyo.jprs.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753347AbaA1CxR (ORCPT ); Mon, 27 Jan 2014 21:53:17 -0500 In-Reply-To: <52E6B80D.7060807@redhat.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: Eric-san, Ted-san; Thank you very much. I am happy now. On 2014/01/28 3:02, Eric Sandeen wrote: > > It will depend on the length of the filenames. But by my calculations, > for average 28-char filenames, it's closer to 30 million. > > There are (4096-32)/8 indices per block, or 508. > There are 2 levels, so 508*508=258064 leaf blocks. > The length of each record for 28 char names would be 32 bytes. > So you can fit 4096/32 = 128 entries per leaf block. > 258064 leaf blocks * 128 entries/bock is 33,032,192 entries. I understand. > I recently made a spreadsheet to calculate this. > I'm not sure if I am doing google docs sharing and protection > correctly, but this might work: > > https://docs.google.com/spreadsheet/ccc?key=0AtdHTZsZ8XoYdE1IUXlDb1RXQkdPM3F4YWpfNGhMbFE&usp=sharing#gid=0 Great! It is useful for us. On 2014/01/28 4:39, Theodore Ts'o wrote: > > Note that there will be some very significant performance problems > well before a directory gets that big. For example, just simply doing > a readdir + stat on all of the files in that directory (or a readdir + > unlink, etc.) will very likely result in extremely unacceptable > performance. Of course, I know that issue. But we have already this directory. $ \ls -f | wc 1933497 1933497 14968002 This is for mail archive. :-( On 2014/01/28 4:48, Eric Sandeen wrote: > > Yep, that's the max possible, not the max useable. ;) Yes, I wanted to know the limitation. Again, Thank you very much. Best Regards, -- Masato minmin Minda Japan Registry Services Co., Ltd. (JPRS)