Performance Hit With Many Files Post: 302293379

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Special Forums Hardware Filesystems, Disks and Memory Performance Hit With Many Files Post 302293379 by otheus on Tuesday 3rd of March 2009 03:58:33 AM

03-03-2009

Registered User

Excellent question! It is indeed filesystem-dependent. Such performance metrics are hard to come by, since there are so many variables, and to do a good apples-apples comparison, you need the same computer with the same disks and install multiple OS's. But it may not be necessary, really, to get such statistics. One can look at the filesystem architecture, directory handling semantics, and conclude one might be better than the other.

Unforatunally, I cannot provide specifics on JFS nor NTFS. However, ReiserFS and modern versions of ext2 (on filesystems created with -O DIR_INDEX), file creation and lookup are very fast; they both use a hash index to find files. So if you know the name of the file, it can be found almost instantly (as I understand it and have experienced). On older versions of ext2, things really started to slow down after the directory entry itself extended to one or more indirect blocks -- maybe 1000 or so.

You do know one way to store large amounts of files is to create a directory hierarchy that is keyed on the filenames themselves? So files named "ergo1802.txt" might be stored in:

Code:

    data/er/go/18/ergo1802.txt

otheus

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scrounge-ntfs

scrounge-ntfs(8)					    BSD System Manager's Manual 					  scrounge-ntfs(8)

NAME

     scrounge-ntfs -- helps retrieve data from corrupted NTFS partitions

SYNOPSIS

     scrounge-ntfs -l disk
     scrounge-ntfs -s disk
     scrounge-ntfs [-m mftoffset] [-c clustersize] [-o outdir] disk start end

DESCRIPTION

     scrounge-ntfs is a utility that can rescue data from corrupted NTFS partitions. It writes the files retrieved to another working file system.
     Certain information about the partition needs to be known in advance.

     The -l mode is meant to be run in advance of the data corruption, with the output stored away in a file. This allows scrounge-ntfs to recover
     data reliably. See the 'NOTES' section below for recover info when this isn't the case.

OPTIONS

     The options are as follows:

     -c 	 The cluster size (in sectors). When not specified a default of 8 is used.

     -l 	 List partition information for a drive. This will only work when the partition table for the given drive is intact.

     -m 	 When recovering data this specifies the location of the MFT from the beginning of the partition (in sectors). If not specified
		 then no directory information can be used, that is, all rescued files will be written to the same directory.

     -o 	 Directory to put rescued files in. If not specified then files will be placed in the current directory.

     -s 	 Search disk for partition information. (Not implemented yet).

     disk	 The raw device used to access the disk which contains the NTFS partition to rescue files from. eg: '/dev/hdc'

     start	 The beginning of the NTFS partition (in sectors).

     end	 The end of the NTFS partition (in sectors)

NOTES

     If you plan on using this program sucessfully you should prepare in advance by storing a copy of the partition information. Use the -l option
     to do this. Eventually searching for disk partition information will be implemented, which will solve this problem.

     When only one partition exists on a disk or you want to rescue the first partition there are ways to guess at the sector sizes and MFT loca-
     tion. See the scrounge-ntfs web page for more info:

     http://memberwebs.com/swalter/software/scrounge/

AUTHOR

     Stef Walter <stef@memberwebs.com>

scrounge-ntfs							   June 1, 2019 						     scrounge-ntfs