11-02-2012
Thanks for posting the update.
Quote:
Originally Posted by
-=XrAy=-
This system has a lot of filesystems with a lot of small files (cobol sources, etc.).
Maybe the insufficent Inode-cache prevent the System to use the whole FS-cache?
I noticed in another project and under different circumstances that the speed with which to acquire file metadata (basically the contents of inodes) can dramatically speed up file operations:
A network relied heavily on NFS-shares and was redesigned to operate from one huge GPFS-datapool (~500TB). The first thing noticeable was that KDE had to be removed from all the clients, because the damn thing tries to create a hidden file-DB at startup. This is fine when you have a local disk with 20k files, but not when you see several millions of them. (It might be possible to tweak KDE somehow to stop that, but nobody bothered to do so. Desktops are a waste of resources anyway.)
The second observable phenomenon was that backup/restore times could be dramatically improved by moving the metadata onto a SSD. It didn't even have to be big in size: 200-300GB would suffice.
Now this fits in well with what you say about cache sizes and metadata caching. Probably AIX file I/O can be improved by tweaking the resources set aside specifically for dealing with file metadata.
Thanks again for sharing.
bakunin
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LEARN ABOUT HPUX
vgcfgrestore
VGCFGRESTORE(8) System Manager's Manual VGCFGRESTORE(8)
NAME
vgcfgrestore - restore volume group descriptor area
SYNOPSIS
vgcfgrestore [-d|--debug] [-f|--file filename] [-l[l]|--list] [-h|--help] [-M|--Metadatatype1|2] [-t|--test] [-v|--verbose] VolumeGroupName
DESCRIPTION
vgcfgrestore allows you to restore the metadata of VolumeGroupName from a text backup file produced by vgcfgbackup. You can specify a
backup file with --file. If no backup file is specified, the most recent one is used. Use --list for a list of the available backup and
archive files of VolumeGroupName.
OPTIONS
-l | --list -- List files pertaining to VolumeGroupName
List metadata backup and archive files pertaining to VolumeGroupName. May be used with the -f option. Does not restore Vol-
umeGroupName.
-f | --file filename -- Name of LVM metadata backup file
Specifies a metadata backup or archive file to be used for restoring VolumeGroupName. Often this file has been created with vgcfg-
backup.
See lvm for common options.
REPLACING PHYSICAL VOLUMES
vgdisplay --partial --verbose will show you the UUIDs and sizes of any PVs that are no longer present. If a PV in the VG is lost and you
wish to substitute another of the same size, use pvcreate --restorefile filename --uuid uuid (plus additional arguments as appropriate) to
initialise it with the same UUID as the missing PV. Repeat for all other missing PVs in the VG. Then use vgcfgrestore --file filename to
restore the volume group's metadata.
SEE ALSO
lvm(8), vgcreate(8)
Sistina Software UK LVM TOOLS 2.02.95(2) (2012-03-06) VGCFGRESTORE(8)