[lustre-discuss] Why certain commands should not be used on Lustre file system

[Shinobu Kinjo]

NASA gives you good understanding using lustre.

http://www.nas.nasa.gov/hecc/support/kb/lustre-best-practices_226.html

Rgds,
Shinobu

On Wed, Feb 10, 2016 at 2:52 PM, Dilger, Andreas <andreas.dilger at intel.com>
wrote:

> On 2016/02/09, 21:16, "lustre-discuss on behalf of
> Prakrati.Agrawal at shell.com<mailto:Prakrati.Agrawal at shell.com>" <
> lustre-discuss-bounces at lists.lustre.org<mailto:
> lustre-discuss-bounces at lists.lustre.org> on behalf of
> Prakrati.Agrawal at shell.com<mailto:Prakrati.Agrawal at shell.com>> wrote:
>
> I read on Lustre best practices that ls –U should be used instead of ls –l
> . I understand that ls –l makes MDS contact all OSS to get all information
> about all files and hence loads it. But, what does ls –U do to avoid it?
>
>        -U     do not sort; list entries in directory order
>
> This is more important for very large directories, since "ls" will read
> all of the entries and stat them before printing anything.  That said, GNU
> ls will still read all of the entries before printing them, so for very
> large directories "find <directory> -ls" is a lot faster to start printing
> entries.
>
> Also, it is said that rm-rf * should not be used. Please can someone
> explain the reason for that.
>
> It is also said that instead lfs find  <directory path> --type f -print0 |
> xargs -0 rm –f should be used. Please explain the reason for this also.
>
> "rm -rf *" will expand "*" onto the command line (done by bash) and if
> there are too many files in the directory (more than about 8MB IIRC) then
> bash will fail to execute the command.  Running "lfs find" (or just plain
> "find") will only print the filenames onto the output and xargs will
> process them in chunks that fit onto a command-line.
>
> Cheers, Andreas
> --
> Andreas Dilger
> Lustre Principal Architect
> Intel High Performance Data Division
>
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