Re: [RFC/PATCH] svnadmin: recover/hotcopy erroring out for old FSFS repositories
On 31 January 2014 05:50, Evgeny Kotkov <evgeny.kotkov_at_visualsvn.com> wrote:
>> This only affects non-sharded repositories with rev-local IDs,
>> i.e. those in SVN 1.4 format. For those, it is writing 3 files
>> instead of 2 per rev now.
> I assume you are talking about r1560723 . If I read the code correctly...
> if ( (!max_files_per_dir || rev % max_files_per_dir == 0)
> && dst_ffd->format >= SVN_FS_FS__MIN_NO_GLOBAL_IDS_FORMAT)
> SVN_ERR(hotcopy_update_current(&dst_youngest, dst_fs, rev, iterpool));
> ...hotcopy now checkpoints after every revision for all non-sharded repositories
> with FSFS format >= 3. So, checkpointing happens for all FSFS format 1/2
> repositories upgraded via 'svnadmin upgrade' (with linear layout), that were
> not fsfs-reshard'ed or dump/loaded into a repository with newer format.
> I am not aware of how many people reshard or dump/load their old repositories
> after upgrade, but I did a quick benchmark for a real-world repository and on my
> machine it shows 7x performance degradation with checkpointing enabled. Is it
> worth the ability to re-run the backup from a checkpoint upon cancellation?
> # svnrdump http://googletest.googlecode.com/svn/trunk/
> # load the dump into a --compatible-version=1.3 repository
> # upgrade the repository with the most recent svnadmin
> # disable checkpointing, benchmark making 100 hotcopy backups:
> real 0m18.741s
> user 0m2.552s
> sys 0m13.432s
> # now enable checkpointing and repeat the benchmark:
> real 2m5.793s
> user 0m0.836s
> sys 0m34.840s
>  http://svn.apache.org/viewvc?view=revision&revision=r1560723
That's what I suspected. In this case I think r1560723 should not be
backported to 1.8.x for the following reasons:
1. Significant performance degradation for 'svnadmin hotcopy' with
2. The change doesn't fix original circular dependency problem in FSFS
3. 'svnadmin recover' writes fake value to CURRENT file which very bad
practice IMHO and could lead undefined consequences.
CTO | VisualSVN | http://www.visualsvn.com
Received on 2014-01-31 11:58:28 CET
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