rotatelogsを利用して日時ローテートさせる設定(以下)にした場合ログが作成されてから86400秒以上で切り替わるとしたらきちんと日次で変わらない事になるので調査。

CustomLog "|/usr/local/apache/bin/rotatelogs /var/log/access_log-%Y-%m-%d 86400 540 " common

86400 540になっているのはrotatelogsがUTC基準だから9時間分のオフセット指定
# 2.0.51以降のバージョンであれば -l オプションでも良いと思う。
http://httpd.apache.org/docs/2.2/ja/programs/rotatelogs.html


ずばりが以下に書いてあったので詳しく調べてませんw
ftp-adminの憂鬱:http://ftp-admin.blogspot.com/2010/03/rotatelogs.html

> 実際にはrotatelogsはtime(2)の返す値を86400秒で丸めてから開始時刻にするので、
> 開始時刻はその日の0時になります。
> したがって、ログファイルが切り替わるのは翌日の0時以降です。

ちなみにapache2.2.21に付属しているrotatelogsのソースは以下

/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * Simple program to rotate Apache logs without having to kill the server.
 *
 * Contributed by Ben Laurie <ben algroup.co.uk>
 *
 * 12 Mar 1996
 *
 * Ported to APR by Mladen Turk <mturk mappingsoft.com>
 *
 * 23 Sep 2001
 *
 * -l option added 2004-06-11
 *
 * -l causes the use of local time rather than GMT as the base for the
 * interval.  NB: Using -l in an environment which changes the GMT offset
 * (such as for BST or DST) can lead to unpredictable results!
 *
 * -f option added Feb, 2008. This causes rotatelog to open/create
 *    the logfile as soon as it's started, not as soon as it sees
 *    data.
 */


#include "apr.h"
#include "apr_lib.h"
#include "apr_strings.h"
#include "apr_errno.h"
#include "apr_file_io.h"
#include "apr_file_info.h"
#include "apr_general.h"
#include "apr_time.h"
#include "apr_getopt.h"

#if APR_HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if APR_HAVE_STRING_H
#include <string.h>
#endif
#if APR_HAVE_STRINGS_H
#include <strings.h>
#endif

#define BUFSIZE         65536
#define ERRMSGSZ        256

#ifndef MAX_PATH
#define MAX_PATH        1024
#endif

static void usage(const char *argv0, const char *reason)
{
    if (reason) {
        fprintf(stderr, "%s\n", reason);
    }
    fprintf(stderr,
            "Usage: %s [-l] [-f] <logfile> "
            "{<rotation time in seconds>|<rotation size in megabytes>} "
            "[offset minutes from UTC]\n\n",
            argv0);
#ifdef OS2
    fprintf(stderr,
            "Add this:\n\nTransferLog \"|%s.exe /some/where 86400\"\n\n",
            argv0);
#else
    fprintf(stderr,
            "Add this:\n\nTransferLog \"|%s /some/where 86400\"\n\n",
            argv0);
    fprintf(stderr,
            "or \n\nTransferLog \"|%s /some/where 5M\"\n\n", argv0);
#endif
    fprintf(stderr,
            "to httpd.conf. The generated name will be /some/where.nnnn "
            "where nnnn is the\nsystem time at which the log nominally "
            "starts (N.B. if using a rotation time,\nthe time will always "
            "be a multiple of the rotation time, so you can synchronize\n"
            "cron scripts with it). At the end of each rotation time or "
            "when the file size\nis reached a new log is started.\n");
    exit(1);
}

static int get_now(int use_localtime, int utc_offset)
{
    apr_time_t tNow = apr_time_now();
    if (use_localtime) {
        /* Check for our UTC offset before using it, since it might
         * change if there's a switch between standard and daylight
         * savings time.
         */
        apr_time_exp_t lt;
        apr_time_exp_lt(&lt, tNow);
        utc_offset = lt.tm_gmtoff;
    }
    return (int)apr_time_sec(tNow) + utc_offset;
}

int main (int argc, const char * const argv[])
{
    char buf[BUFSIZE], buf2[MAX_PATH], errbuf[ERRMSGSZ];
    int tLogEnd = 0, tRotation = 0, utc_offset = 0;
    unsigned int sRotation = 0;
    int nMessCount = 0;
    apr_size_t nRead, nWrite;
    int use_strftime = 0;
    int use_localtime = 0;
    int bypass_io = 0;
    int now = 0;
    const char *szLogRoot;
    apr_file_t *f_stdin, *nLogFD = NULL, *nLogFDprev = NULL;
    apr_pool_t *pool;
    apr_pool_t *pfile = NULL;
    apr_pool_t *pfile_prev = NULL;
    apr_getopt_t *opt;
    apr_status_t rv;
    char c;
    const char *optarg;
    char *ptr = NULL;

    apr_app_initialize(&argc, &argv, NULL);
    atexit(apr_terminate);

    apr_pool_create(&pool, NULL);
    apr_getopt_init(&opt, pool, argc, argv);
    while ((rv = apr_getopt(opt, "lf", &c, &optarg)) == APR_SUCCESS) {
        switch (c) {
        case 'l':
            use_localtime = 1;
            break;
        case 'f':
            bypass_io = 1;
            break;
        }
    }

    if (rv != APR_EOF) {
        usage(argv[0], NULL /* specific error message already issued */ );
    }

    if (opt->ind + 2 != argc && opt->ind + 3 != argc) {
        usage(argv[0], "Incorrect number of arguments");
    }

    szLogRoot = argv[opt->ind++];

    ptr = strchr(argv[opt->ind], 'M');
    if (ptr) { /* rotation based on file size */
        if (*(ptr+1) == '\0') {
            sRotation = atoi(argv[opt->ind]) * 1048576;
        }
        if (sRotation == 0) {
            usage(argv[0], "Invalid rotation size parameter");
        }
    }
    else { /* rotation based on elapsed time */
        tRotation = atoi(argv[opt->ind]);
        if (tRotation <= 0) {
            usage(argv[0], "Invalid rotation time parameter");
        }
    }
    opt->ind++;

    if (opt->ind < argc) { /* have UTC offset */
        if (use_localtime) {
            usage(argv[0], "UTC offset parameter is not valid with -l");
        }
        utc_offset = atoi(argv[opt->ind]) * 60;
    }

    use_strftime = (strchr(szLogRoot, '%') != NULL);
    if (apr_file_open_stdin(&f_stdin, pool) != APR_SUCCESS) {
        fprintf(stderr, "Unable to open stdin\n");
        exit(1);
    }

    for (;;) {
        nRead = sizeof(buf);
        /*
         * Bypass reading stdin if we are forcing the logfile
         * to be opened as soon as we start. Since we won't be
         * writing anything, we just want to open the file.
         * First time through is the only time we do this
         * since we reset bypass_io after the 1st loop
         */
        if (!bypass_io) {
            if (apr_file_read(f_stdin, buf, &nRead) != APR_SUCCESS) {
                exit(3);
            }
        }
        if (tRotation) {
            now = get_now(use_localtime, utc_offset);
            if (nLogFD != NULL && now >= tLogEnd) {
                nLogFDprev = nLogFD;
                nLogFD = NULL;
            }
        }
        else if (sRotation) {
            apr_finfo_t finfo;
            apr_off_t current_size = -1;

            if ((nLogFD != NULL) &&
                (apr_file_info_get(&finfo, APR_FINFO_SIZE, nLogFD) == APR_SUCCESS)) {
                current_size = finfo.size;
            }

            if (current_size > sRotation) {
                nLogFDprev = nLogFD;
                nLogFD = NULL;
            }
        }
        else {
            fprintf(stderr, "No rotation time or size specified\n");
            exit(2);
        }

        if (nLogFD == NULL) {
            int tLogStart;
            apr_status_t rv;

            if (tRotation) {
                tLogStart = (now / tRotation) * tRotation;
            }
            
            (1326655971 / 600) * 600
            else {
                tLogStart = get_now(use_localtime, utc_offset);
            }

            if (use_strftime) {
                apr_time_t tNow = apr_time_from_sec(tLogStart);
                apr_time_exp_t e;
                apr_size_t rs;

                apr_time_exp_gmt(&e, tNow);
                apr_strftime(buf2, &rs, sizeof(buf2), szLogRoot, &e);
            }
            else {
                apr_snprintf(buf2, sizeof(buf2), "%s.%010d", szLogRoot, tLogStart);
            }
            tLogEnd = tLogStart + tRotation;
            pfile_prev = pfile;
            apr_pool_create(&pfile, pool);
            rv = apr_file_open(&nLogFD, buf2, APR_WRITE | APR_CREATE | APR_APPEND,
                               APR_OS_DEFAULT, pfile);
            if (rv != APR_SUCCESS) {
                char error[120];

                apr_strerror(rv, error, sizeof error);

                /* Uh-oh. Failed to open the new log file. Try to clear
                 * the previous log file, note the lost log entries,
                 * and keep on truckin'. */
                if (nLogFDprev == NULL) {
                    fprintf(stderr, "Could not open log file '%s' (%s)\n", buf2, error);
                    exit(2);
                }
                else {
                    nLogFD = nLogFDprev;
                    apr_pool_destroy(pfile);
                    pfile = pfile_prev;
                    /* Try to keep this error message constant length
                     * in case it occurs several times. */
                    apr_snprintf(errbuf, sizeof errbuf,
                                 "Resetting log file due to error opening "
                                 "new log file, %10d messages lost: %-25.25s\n",
                                 nMessCount, error);
                    nWrite = strlen(errbuf);
                    apr_file_trunc(nLogFD, 0);
                    if (apr_file_write(nLogFD, errbuf, &nWrite) != APR_SUCCESS) {
                        fprintf(stderr, "Error writing to the file %s\n", buf2);
                        exit(2);
                    }
                }
            }
            else if (nLogFDprev) {
                apr_file_close(nLogFDprev);
                if (pfile_prev) {
                    apr_pool_destroy(pfile_prev);
                }
            }
            nMessCount = 0;
        }
        /*
         * If we just bypassed reading stdin, due to bypass_io,
         * then we have nothing to write, so skip this.
         */
        if (!bypass_io) {
            nWrite = nRead;
            rv = apr_file_write(nLogFD, buf, &nWrite);
            if (rv == APR_SUCCESS && nWrite != nRead) {
                /* buffer partially written, which for rotatelogs means we encountered
                 * an error such as out of space or quota or some other limit reached;
                 * try to write the rest so we get the real error code
                 */
                apr_size_t nWritten = nWrite;

                nRead  = nRead - nWritten;
                nWrite = nRead;
                rv = apr_file_write(nLogFD, buf + nWritten, &nWrite);
            }
            if (nWrite != nRead) {
                char strerrbuf[120];
                apr_off_t cur_offset;
                
                cur_offset = 0;
                if (apr_file_seek(nLogFD, APR_CUR, &cur_offset) != APR_SUCCESS) {
                    cur_offset = -1;
                }
                apr_strerror(rv, strerrbuf, sizeof strerrbuf);
                nMessCount++;
                apr_snprintf(errbuf, sizeof errbuf,
                             "Error %d writing to log file at offset %" APR_OFF_T_FMT ". "
                             "%10d messages lost (%s)\n",
                             rv, cur_offset, nMessCount, strerrbuf);
                nWrite = strlen(errbuf);
                apr_file_trunc(nLogFD, 0);
                if (apr_file_write(nLogFD, errbuf, &nWrite) != APR_SUCCESS) {
                    fprintf(stderr, "Error writing to the file %s\n", buf2);
                exit(2);
                }
            }
            else {
                nMessCount++;
            }
        }
        else {
           /* now worry about reading 'n writing all the time */
           bypass_io = 0;
        }
    }
    /* Of course we never, but prevent compiler warnings */
    return 0;
}