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The Graveyard - Products No Longer Supported => D-Link Storage => DNS-323 => Topic started by: ecb on March 20, 2009, 06:01:46 AM

Title: -slow- internal data transfer between drives & incremental backups
Post by: ecb on March 20, 2009, 06:01:46 AM
Hi, I'm in the process of doing a backup between HDs in my 323.  It seems to be working OK but it is extremely slow.  My guess is that it will take around 2 weeks to complete the transfer.  I am transferring a very large number of files though they aren't very large (a few million at least, most of them are fairly small).  This transfer is probably 10x slower than copying files directly from my PC to one of the drives.  Is this expected?

If this is the speed I should expect I have some concerns about doing incremental backups.  I won't be doing an incremental scan across the full HD but I will still need to keep a large number of files in sync on a fairly regular basis.  The changes will be minor from backup to backup but I still wonder how long it will take the 323 to even scan a large group of times.  Should I expect long processing times in doing an incremental backup where you have a large number of files but only a few change?  How will this impact my ability to do other things at the same time with the 323 like stream video to my 360?  Does one thread take priority over the other or do the two thrash back and forth?

Thanks for the advice.
Title: Re: -slow- internal data transfer between drives & incremental backups
Post by: fordem on March 20, 2009, 10:15:01 AM
Are you running an "internal data transfer" or are you transferring data from one drive across the network to your computer and then back to the other drive - these are actually two different things - significantly different.

With large numbers of small files, throughput is generally low.
Title: Re: -slow- internal data transfer between drives & incremental backups
Post by: ecb on March 20, 2009, 10:34:06 AM
it's running purely internal to the drive and i'm not accessing the drive in any other way.  it should be doing the transfer as fast as it can, which isn't terribly fast.  :\
Title: Re: -slow- internal data transfer between drives & incremental backups
Post by: ECF on March 20, 2009, 03:07:38 PM
How are you doing this transfer? What are your procedure steps?
Title: Re: -slow- internal data transfer between drives & incremental backups
Post by: ecb on March 20, 2009, 06:16:01 PM
i log in to my router, go to downloads and set up a scheduled transfer between Volume_1 and Volume_2 and set the time to force the transfer to happen immediately.  that's it.  this initial transfer is not set up to be incremental so it's not like any of that logic/checking is slowing the process down.  it's just a very slow transfer.
Title: Re: -slow- internal data transfer between drives & incremental backups
Post by: ecb on March 20, 2009, 06:28:05 PM
oh and to put more concrete terms to all of this it took 20 minutes to transfer 485 files which are in total about 4 MBytes.  that's ridiculously slow.  it's definitely the # of files that's affecting transfer rates.  i can see that very large individual files are transferred quickly; multiple MBytes per second.

any official statement on this?
Title: Re: -slow- internal data transfer between drives & incremental backups
Post by: bripab007 on March 21, 2009, 08:55:54 PM
Part of the problem is that, I believe, it's using the DNS-323's FTP service to complete the task of transferring files disk-to-disk, and FTP is just a slow method for moving a lot of files because of all the pre- and post-copy checks associated with FTP transfers (e.g. check if file exists, compare rights of files, check filesize, copy file, check that file size on new location is correct, check that file rights are correct, etc.).  When I used to work on websites, I dreaded uploading a completely new copy of my company's website to our webserver because there were so many files that it took over an hour to transfer the ~125MB site.
Title: Re: -slow- internal data transfer between drives & incremental backups
Post by: ecb on March 21, 2009, 10:02:27 PM
Part of the problem is that, I believe, it's using the DNS-323's FTP service to complete the task of transferring files disk-to-disk, and FTP is just a slow method for moving a lot of files because of all the pre- and post-copy checks associated with FTP transfers (e.g. check if file exists, compare rights of files, check filesize, copy file, check that file size on new location is correct, check that file rights are correct, etc.).  When I used to work on websites, I dreaded uploading a completely new copy of my company's website to our webserver because there were so many files that it took over an hour to transfer the ~125MB site.

thanks for the info.  would be interesting to know if it is actually using FTP to copy between two local drives.  at least if that's the case i can be quite sure that the contents are extremely well verified.  ;)