Migrate large amount of small files

[Jin Guojun]

The major factor affects the performance the the number of files in "PER" directory.
If I got impression correct, there are 5M files in JUST one directory. If this is true, then it is the problem.

The best way to avoid performance penalty is to sort different files into differet named directories. 
Each directory should contain about 1K files or less. Carefully tuned FS may have better performance for a directory conataining a few thousand files, but no more.

If files are created by some state machine automatically, and you do not have a good sorting algorithm for directory naming, use Year-Month-week for auto directory naming.

--- On Sun, 10/11/09, Mike Tancsa <mike at sentex.net> wrote:

> From: Mike Tancsa <mike at sentex.net>
> Subject: Re: Migrate large amount of small files
> To: net.help at m2k.com.tw, "freebsd-performance" <freebsd-performance at freebsd.org>
> Date: Sunday, October 11, 2009, 9:07 PM
> At 11:46 AM 10/10/2009, Ckcheng
> wrote:
> >Hi all,
> >Currently, I have a directory with over 5M small files
> (1~32K). Now,
> >I want to transfer this directory to another machine
> and found
> >that it's extremely slow and painful process. I tried
> the following
> >method:
> 
> It might help if you mount all -onoatime as well as bump up
> 
> vfs.ufs.dirhash_maxmem to 4x the default size
> 
>          ---Mike
> 
> >1. rsync
> >2. tar via ssh
> >3. tar via nc
> >(all take hours and hours to finish)
> >
> >None of them is able to give me a reasonable migration
> time. So, I'm
> >here for asking help. Any suggestion is extremely
> welcomed. Thank you.
> >
> >Btw, here is brief information of my server. (both
> machines are the same)
> >
> >OS: FreeBSD 6.4-Stable 64Bit
> >CPU: 2 x Xeon L5420 2.50GHz
> >RAM: 2 x 2G ECC DDR2-667 (full buffered)
> >DISK: Seagate Barracuda ES 16MB (SATA 300)
> >Network: 1Gbps (Broadcom BCM5708)
> >Filesystem: UFS2
> >
> >Regards,
> >_______________________________________________
> >freebsd-performance at freebsd.org
> mailing list
> >http://lists.freebsd.org/mailman/listinfo/freebsd-performance
> >To unsubscribe, send any mail to "freebsd-performance-unsubscribe at freebsd.org"
> 
> --------------------------------------------------------------------
> Mike Tancsa,           
>                
>           tel +1 519 651 3400
> Sentex Communications,         
>                
>   mike at sentex.net
> Providing Internet since 1994       
>             www.sentex.net
> Cambridge, Ontario Canada         
>            
>    www.sentex.net/mike
> 
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