[mythtv-users] Disk space is not freed from deleted recording until mythbackend exits

[Yeechang Lee]

Jim O'Neill <oneillji at gmail.com> says:
> I just created a script to execute df every 60 seconds and ran this
> for about 20 minutes between recordings.  I'm seeing 500 KB +/- a
> few bytes being deleted every minute.  If my math is correct this
> works out to 16 = hours to completely delete a 500 MB recording.

I can testify that the truncation method works, and works well;
however I don't know which of the patches listed at
<URL:http://svn.mythtv.org/trac/ticket/1835> are in the current SVN,
and if 1835-v5.patch is anything like 1835-v4.patch it may be
broken. Please see
<URL:http://www.gossamer-threads.com/lists/mythtv/users/208763#208763>
for my experiences with different iterations of the patch with
0.19-fixes.

I currently use the following patch on gradual-delete3.patch:

*** gradual-delete3.patch       2006-06-14 23:36:17.571885518 -0700
--- gradual-delete3.patch.orig  2006-06-12 18:15:14.548890000 -0700
***************
*** 86,99 ****
  +int MainServer::TruncateAndClose(int fd, QString filename)
  +{
  +    QMutexLocker locker(&truncatelock);
! +    const int sleep_time = 15; // time between truncation steps in seconds
  +    int err;
  +    size_t increment;
  +    struct stat buf;
  +
  +    // Compute the truncate increment such that we delete 20% faster than the
  +    // maximum recording rate.
! +    increment = (m_expirer->MaxRecordRate() * sleep_time * 9) / 5;
  +
  +    VERBOSE(VB_FILE,
  +            QString("Truncating '%1' by %2 MB every %3 seconds")
--- 86,99 ----
  +int MainServer::TruncateAndClose(int fd, QString filename)
  +{
  +    QMutexLocker locker(&truncatelock);
! +    const int sleep_time = 2; // time between truncation steps in seconds
  +    int err;
  +    size_t increment;
  +    struct stat buf;
  +
  +    // Compute the truncate increment such that we delete 20% faster than the
  +    // maximum recording rate.
! +    increment = (m_expirer->MaxRecordRate() * sleep_time * 6) / 5;
  +
  +    VERBOSE(VB_FILE,
  +            QString("Truncating '%1' by %2 MB every %3 seconds")

In case the annoyingly-broken mailserver breaks the patch's
formatting, the only changes I've made are to adjust sleep_time to 15
and "sleep_time * 9) / 5;" to "sleep_time * 6) / 5;".

-- 
Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US