Re: Archive Log Size

archive_lag_target is 900

On Tue, Mar 9, 2021 at 2:33 PM Tim Gorman <tim.evdbt_at_gmail.com> wrote:

> What is the value of ARCHIVE_LAG_TARGET?
>
>
> On 3/9/2021 11:29 AM, Henry Poras wrote:
>
> Basically that is it. Redo logs are 256M, archive logs are ~40M. There was
> a similar issue/thread in this list ~6 weeks ago, but the solution to that
> system doesn't fit with this case. Hope that helps.
>
> Henry
>
>
> On Tue, Mar 9, 2021 at 2:23 PM Chris Taylor <
> christopherdtaylor1994_at_gmail.com> wrote:
>
>> So what is the issue here exactly? I''ve read through this thread a few
>> times without clearly understanding the "problem" .
>>
>> It seems like you're wondering about why the archivelogs are smaller than
>> the redo logs maybe? But I'm not sure if that is the issue or not.
>>
>> Chris
>>
>>
>> On Tue, Mar 9, 2021 at 1:51 PM Henry Poras <henry.poras_at_gmail.com> wrote:
>>
>>> I wonder if there is any way to see if the problem is local or from the
>>> standby without temporarily disabling the standby. It would be nice to be
>>> able to eliminate one of those two causes.
>>>
>>> Henry
>>>
>>> On Tue, Mar 9, 2021 at 12:54 PM Henry Poras <henry.poras_at_gmail.com>
>>> wrote:
>>>
>>>> I liked that idea. Unfortunately,
>>>>
>>>> *physical standby*:sys_at_ohcopp2> select distinct bytes from v$log;
>>>>
>>>>
>>>>
>>>> BYTES
>>>>
>>>> ----------
>>>>
>>>> 268435456
>>>>
>>>>
>>>>
>>>> 1 row selected.
>>>>
>>>> *physical standby*:sys_at_ohcopp2> select distinct bytes from
>>>> v$standby_log;
>>>>
>>>>
>>>>
>>>> BYTES
>>>>
>>>> ----------
>>>>
>>>> 268435456
>>>>
>>>>
>>>>
>>>> 1 row selected.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> *primary*:sys_at_ohcops1> select distinct bytes from v$log;
>>>>
>>>>
>>>>
>>>> BYTES
>>>>
>>>> ----------
>>>>
>>>> 268435456
>>>>
>>>>
>>>>
>>>> 1 row selected.
>>>>
>>>>
>>>>
>>>> On Tue, Mar 9, 2021 at 12:02 PM Jonathan Lewis <jlewisoracle_at_gmail.com>
>>>> wrote:
>>>>
>>>>>
>>>>> That explains the LGWR/ARCH oddity.
>>>>>
>>>>> Next, let me display my ignorance: is it possible to configure your
>>>>> standby with standby log files that are SMALLER than the primary log files
>>>>> - I think it used to be necessary to have them matching in size, but maybe
>>>>> that's changed since the good old days (of 10g). If a standby can survive
>>>>> with standby log file smaller than primary log files then maybe your 40 -
>>>>> 45MB is being dictated by the size of your standby log files.
>>>>>
>>>>> Regards
>>>>> Jonathan Lewis
>>>>>
>>>>>
>>>>>
>>>>> On Tue, 9 Mar 2021 at 16:35, Henry Poras <henry.poras_at_gmail.com>
>>>>> wrote:
>>>>>
>>>>>> Current parameter settings (same on all nodes) are:
>>>>>>
>>>>>> log_archive_dest_1
>>>>>> LOCATION=USE_DB_RECOVERY_FILE_DEST VALID_FOR=(ALL_LOGFILES,ALL_ROLES)
>>>>>> DB_UNIQUE_NAME=xxxx
>>>>>>
>>>>>> log_archive_dest_2 SERVICE=xxxx LGWR ASYNC
>>>>>> VALID_FOR=(ONLINE_LOGFILES,PRIMARY_ROLE) DB_UNIQUE_NAME=xxxx
>>>>>>
>>>>>> log_archive_dest_state_1 enable
>>>>>>
>>>>>> log_archive_dest_state_2 ENABLE
>>>>>>
>>>>>> log_archive_max_processes 4
>>>>>>
>>>>>> log_archive_duplex_dest
>>>>>>
>>>>>> log_archive_format ARC%S_%R.%T
>>>>>>
>>>>>>
>>>>>>
>>>>>> So log_archive_dest_2 has the deprecated LGWR parameter. It's dest_1,
>>>>>> using FRA which is using ARCH. Huh?
>>>>>>
>>>>>> Henry
>>>>>>
>>>>>> On Tue, Mar 9, 2021 at 8:45 AM Henry Poras <henry.poras_at_gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> Jonathan,
>>>>>>> I have to admit I was also not expecting both LGWR and ARCH and only
>>>>>>> came across that because you suggested looking for creator. I didn't put
>>>>>>> this standby together, so I'll do a bit of digging to see how it is
>>>>>>> constructed. One question though (and the reason I didn't head down this
>>>>>>> path earlier). If archive_lag_time=900 on all instances, what is the
>>>>>>> hypothesis where the standby impacts the archive log size?
>>>>>>>
>>>>>>> Thanks again.
>>>>>>> Henry
>>>>>>>
>>>>>>>
>>>>>>> On Tue, Mar 9, 2021 at 4:43 AM Jonathan Lewis <
>>>>>>> jlewisoracle_at_gmail.com> wrote:
>>>>>>>
>>>>>>>> Interesting that of the two archived copies one is created by ARCH
>>>>>>>> and the other by LGWR.
>>>>>>>> What do your log_archive_dest_1 and log_archive_dest_2 look like ?
>>>>>>>> For completeness I guess it's also worth checking
>>>>>>>>
>>>>>>>> log_archive_dest_state_1 and log_archive_dest_state_2
>>>>>>>> log_archive_max_processes
>>>>>>>>
>>>>>>>> log_archive_duplex_dest
>>>>>>>> log_archive_format
>>>>>>>> log_archive_local_first
>>>>>>>>
>>>>>>>> What sort of standby setup do you have?
>>>>>>>>
>>>>>>>> Regards
>>>>>>>> Jonathan Lewis
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Mon, 8 Mar 2021 at 19:39, Henry Poras <henry.poras_at_gmail.com>
>>>>>>>> wrote:
>>>>>>>>
>>>>>>>>> Hi Jonathan,
>>>>>>>>> Thanks for responding so quickly.
>>>>>>>>>
>>>>>>>>> As expected, we have 2 public threads and no private threads
>>>>>>>>> (RAC). The sizes of log_buffer, Redo Size, Fixed Size, public thread size
>>>>>>>>> as documented above are identical for all three nodes.
>>>>>>>>>
>>>>>>>>> Looking at v$instance, all nodes have been up for ~10 days (not
>>>>>>>>> identical startup_time, but within a day) with status of OPEN.
>>>>>>>>>
>>>>>>>>> I can't find any clues in v$archived_log
>>>>>>>>> primary:sys_at_ohcops1> l
>>>>>>>>> 1 select * from (
>>>>>>>>> 2 select dest_id, thread#, sequence#, creator, first_time from
>>>>>>>>> v$archived_log
>>>>>>>>> 3 order by first_time desc, thread# asc, dest_id asc
>>>>>>>>> 4 )
>>>>>>>>> 5* where rownum <=20
>>>>>>>>> primary:sys_at_ohcops1> /
>>>>>>>>>
>>>>>>>>> DEST_ID THREAD# SEQUENCE# CREATOR FIRST_TIME
>>>>>>>>> ---------- ---------- ---------- ------- -------------------
>>>>>>>>> 1 2 1056302 ARCH 08-03-2021 20:34:11
>>>>>>>>> 2 2 1056302 LGWR 08-03-2021 20:34:11
>>>>>>>>> 1 1 1126141 ARCH 08-03-2021 20:34:06
>>>>>>>>> 2 1 1126141 LGWR 08-03-2021 20:34:06
>>>>>>>>> 1 3 1164895 ARCH 08-03-2021 20:33:47
>>>>>>>>> 2 3 1164895 LGWR 08-03-2021 20:33:47
>>>>>>>>> 1 3 1164894 ARCH 08-03-2021 20:32:26
>>>>>>>>> 2 3 1164894 LGWR 08-03-2021 20:32:26
>>>>>>>>> 1 2 1056301 ARCH 08-03-2021 20:32:20
>>>>>>>>> 2 2 1056301 LGWR 08-03-2021 20:32:20
>>>>>>>>> 1 1 1126140 ARCH 08-03-2021 20:32:15
>>>>>>>>> 2 1 1126140 LGWR 08-03-2021 20:32:15
>>>>>>>>> 1 3 1164893 ARCH 08-03-2021 20:30:50
>>>>>>>>> 2 3 1164893 LGWR 08-03-2021 20:30:50
>>>>>>>>> 1 2 1056300 ARCH 08-03-2021 20:30:29
>>>>>>>>> 2 2 1056300 LGWR 08-03-2021 20:30:29
>>>>>>>>> 1 1 1126139 ARCH 08-03-2021 20:30:09
>>>>>>>>> 2 1 1126139 LGWR 08-03-2021 20:30:09
>>>>>>>>> 1 3 1164892 ARCH 08-03-2021 20:29:32
>>>>>>>>> 2 3 1164892 LGWR 08-03-2021 20:29:32
>>>>>>>>>
>>>>>>>>> 20 rows selected.
>>>>>>>>>
>>>>>>>>> I'll keep looking.
>>>>>>>>>
>>>>>>>>> Henry
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Sat, Mar 6, 2021 at 3:41 AM Jonathan Lewis <
>>>>>>>>> jlewisoracle_at_gmail.com> wrote:
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> RAC doesn't use private redo - so with 32 CPUs we'd expect two
>>>>>>>>>> public threads with (granule - fixed - overheads)/2 as the log buffer size.
>>>>>>>>>> Is this happening on all three instances (redo threads)?
>>>>>>>>>> If you report the "first_time" from v$archived_log can you see a
>>>>>>>>>> pattern to the timing of the switch.
>>>>>>>>>> Is there any clue in the "creator" from v$archived_log ?
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> One possible explanation for this (assuming you've discounted all
>>>>>>>>>> the usual suspects): Are all three instances active when this happens?
>>>>>>>>>> I haven't checked recently but when an instance is down the
>>>>>>>>>> active instances may be "kicking" it (KK lock) on a regular basis to do a
>>>>>>>>>> log file switch so that all instances have archived log files with SCNs
>>>>>>>>>> that are reasonably close to each other. Maybe there's a side effect (or
>>>>>>>>>> timing issue, or bug) related to this that means the kicking is happening
>>>>>>>>>> too frequently and you're not getting through a lot of redo before it
>>>>>>>>>> happens.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Regards
>>>>>>>>>> Jonathan Lewis
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Fri, 5 Mar 2021 at 20:39, Henry Poras <henry.poras_at_gmail.com>
>>>>>>>>>> wrote:
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> - I was just rereading this thread and ran into a slightly
>>>>>>>>>>> different case I am just starting to dig into. My environment is 11.2.0.4
>>>>>>>>>>> RAC (3 nodes).
>>>>>>>>>>>
>>>>>>>>>>> The rough breakdown:
>>>>>>>>>>> Granule size: 256M
>>>>>>>>>>> > select * from v$sga;
>>>>>>>>>>>
>>>>>>>>>>> NAME VALUE
>>>>>>>>>>> -------------------- ----------
>>>>>>>>>>> Fixed Size 2269072
>>>>>>>>>>> Variable Size 3.9460E+10
>>>>>>>>>>> Database Buffers 8.8584E+10
>>>>>>>>>>> Redo Buffers 227807232
>>>>>>>>>>> cpu_count: 32
>>>>>>>>>>> log_buffer: 220798976
>>>>>>>>>>> public threads: 2 public (no private) 105M each
>>>>>>>>>>>
>>>>>>>>>>> primary:sys_at_ohcops1> l
>>>>>>>>>>> 1 select
>>>>>>>>>>> 2 indx,
>>>>>>>>>>> 3 total_bufs_kcrfa,
>>>>>>>>>>> 4 strand_size_kcrfa,
>>>>>>>>>>> 5 index_kcrf_pvt_strand,
>>>>>>>>>>> 6 space_kcrf_pvt_strand
>>>>>>>>>>> 7 from
>>>>>>>>>>> 8* x$kcrfstrand
>>>>>>>>>>> primary:sys_at_ohcops1> /
>>>>>>>>>>>
>>>>>>>>>>> INDX TOTAL_BUFS_KCRFA STRAND_SIZE_KCRFA
>>>>>>>>>>> INDEX_KCRF_PVT_STRAND SPACE_KCRF_PVT_STRAND
>>>>>>>>>>> ---------- ---------------- -----------------
>>>>>>>>>>> --------------------- ---------------------
>>>>>>>>>>> 0 215624 110399488
>>>>>>>>>>> 0 0
>>>>>>>>>>> 1 215624 110399488
>>>>>>>>>>> 0 0
>>>>>>>>>>>
>>>>>>>>>>> redo logs: 256M
>>>>>>>>>>> archive logs: 40-43M
>>>>>>>>>>>
>>>>>>>>>>> So if each public thread takes 105M, I have ~~46M left over.
>>>>>>>>>>> Filling one thread and switching, as discussed in Jonathan's article,
>>>>>>>>>>> should give me archive logs of ~105 M. Instead, I am getting an archive log
>>>>>>>>>>> of ~ the rump size in the redo (256-105-105=46M).
>>>>>>>>>>>
>>>>>>>>>>> I checked the obvious (not a manual log switch, not
>>>>>>>>>>> archive_lag_target).
>>>>>>>>>>> I'll chime in if I find something interesting. Also wondering if
>>>>>>>>>>> any obvious things I'm missing off the top.
>>>>>>>>>>>
>>>>>>>>>>> Henry
>>>>>>>>>>>
>>>>>>>>>>> ===================================================================
>>>>>>>>>>>
>>>>>>>>>>>
>

--
http://www.freelists.org/webpage/oracle-l