MLS Backup time

Discussions around using and interfacing with the Church MLS program.
sammyko
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MLS Backup time

Postby sammyko » Fri Jun 29, 2012 9:53 am

I find that the backup time for MLS is over 2 mins.

Does it sound reasonable?

MLS will always ask for backup after changing finance data. I wish a backup can take a shorter time.

russellhltn
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Postby russellhltn » Fri Jun 29, 2012 10:13 am

You may wish to read MLS Backup file size growing.
Have you searched the Wiki?
Try using a Google search by adding "site:tech.lds.org/wiki" to the search criteria.

sammyko
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Postby sammyko » Fri Jun 29, 2012 10:58 am

Thank you. I will take a try ... removing some of the old statements.

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shawndowler
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Postby shawndowler » Sun Jul 01, 2012 12:36 pm

It should not take nearly this long. It has been pointed out before that the extreme slowness is due to the backup operation using unbuffered writes. A patch was even submitted to correct the issue, but it has never made it into the official MLS builds, unfortunately. It should take less than 1 second to write such a small amount of data. I would be happy if it took 5 seconds at this point.

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aebrown
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Postby aebrown » Sun Jul 01, 2012 5:00 pm

mailman0 wrote:It should not take nearly this long. It has been pointed out before that the extreme slowness is due to the backup operation using unbuffered writes. A patch was even submitted to correct the issue, but it has never made it into the official MLS builds, unfortunately. It should take less than 1 second to write such a small amount of data. I would be happy if it took 5 seconds at this point.


Although I agree that the backup could be significantly faster, your estimate of under a second is far off from a realistic backup time. You're completely ignoring all the logic involved in reading the data from the database. It's not at all clear that your theory of unbuffered write operations is the only or even the primary factor in the time taken for backups.
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allenjpl
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Postby allenjpl » Mon Jul 02, 2012 9:49 pm

aebrown wrote:Although I agree that the backup could be significantly faster, your estimate of under a second is far off from a realistic backup time. You're completely ignoring all the logic involved in reading the data from the database. It's not at all clear that your theory of unbuffered write operations is the only or even the primary factor in the time taken for backups.


On the same note, though, it takes significantly less time to copy and paste a backup then it does for MLS to create a backup. So, for example, if you are making two backups (one to the hard drive and one to a flash drive), it is much quicker to have MLS make the first backup, and then just copy the file to the flash drive.

vandemerwewj
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Postby vandemerwewj » Tue Jul 03, 2012 3:08 pm

mailman0 wrote:It should not take nearly this long. It has been pointed out before that the extreme slowness is due to the backup operation using unbuffered writes. A patch was even submitted to correct the issue, but it has never made it into the official MLS builds, unfortunately. It should take less than 1 second to write such a small amount of data. I would be happy if it took 5 seconds at this point.


I've read the articles about buffered vs. unbuffered writes and this is not the issue with MLS backup speed. These articles simply talk about writing data to a file and don't address compression, encryption or reading from data source. And an MLS backup doesn't contain a small amount of data. If you have a 500 KB backup (without any reports), there is probably between 2.5 MB and 3 MB of data contained in the backup. A 19.9 MB backup would probably contain 3 MB of database data and 40 MB of PDF files. Also take into account the machines in the clerks' office. There is no mention of the machines on which the "buffered tests" are being run, or the amount of memory available, or the amount of memory already allocated.

Currently MLS reads the database info and then writes the data as a Stream through a compression object which is chained through an encryption object and then to a temp file. This temp file is then copied to the final location. The last copy is a carry over from the time when we backed up to floppy disks and sometimes needed to split the file between multiple floppies. That may be what people are seeing as an "unbuffered write".

There are some inefficiencies that are being looked at, but hardware is a lot of the problem. I hate to say it, but a backup, on my machine, of a stake database with no reports - 10 seconds.

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aebrown
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Postby aebrown » Tue Jul 03, 2012 3:22 pm

vandemerwewj wrote:There are some inefficiencies that are being looked at, but hardware is a lot of the problem. I hate to say it, but a backup, on my machine, of a stake database with no reports - 10 seconds.


Hardware is definitely a big factor. It's interesting to hear how fast a backup is on your machine, but my guess is that you have a developer machine with a much faster multi-core processor with a ton of memory and a very fast disk drive. Since that's not the profile for machines that actually do backups out in the field, it's not a very helpful data point.

I carefully delete all the finance reports that I can as soon as I print them, but I have no option to delete the dozens of IROPs that get downloaded to my stake's MLS. I have 3.5 years of financial data at this point, and 3000+ stake members. My stake MLS backups take multiple minutes, and it doesn't make a significant difference whether I go to the hard drive or to a flash drive. The only control I have is trying to do backups as infrequently as possible.
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kisaac
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Postby kisaac » Wed Jul 04, 2012 1:42 pm

aebrown wrote:The only control I have is trying to do backups as infrequently as possible.
I guarantee this same line of thought is happening widespread, due to the backup time length!

And it certainly is not what aebrown was referring to with his comment, but that is the outcome of backups that approach 5 minutes! While I certainly will spread the word that the quickest way to make multiple back-ups is to make one and then copy it, I'm afraid this won't really be happening as a practice either.

Is there a solution on the developer side?

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jeromer7
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Postby jeromer7 » Sat Jul 07, 2012 2:43 pm

aebrown wrote:I carefully delete all the finance reports that I can as soon as I print them...


You must have noticed that along with IROPS, the UFS and CFS are no longer able to be removed. I have copies in my stake MLS back to November 2011 that do not have a "remove" option associated with the entry.
JLR


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