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Operating Systems AIX AIX hdisk Mirror vs alt_clone Post 303033919 by vbe on Sunday 14th of April 2019 11:02:54 AM
Old 04-14-2019
Not sure I understood your request...
Quote:
I have two hdisk in Power7 machine, the rootvg on hdisk0.
OK..
So I should understand of which one is used in rootvg
Quote:
So to make a disk redundancy should make mirror or alt_clone and what is the different.
This is more tricky... my question is what are you trying to achieve, depending and the answer, you can decide what is best
If you are looking to suppress a SPOF then you should head for a mirror, but this only makes sense if you have true physical internal disk
the only other case I see ( which was true for me a while ago...) is because you are on a san that is duplicated ( 2 bays in mirror on 2 different sites...) only now most big bays do that natively...
So if you are not in those configurations alt_clone is the way to go...
The difference ?
in mirror in case of failure you continue to be up and working with the remaining disk.. its transparent but if you forget to replace the disk and it crashes...
alt_clone, is making a clone of that disk, and so you can boot from it but it will be used only on request... e.g. you patch and something goes wrong, you boot on your alternate which is normally in the situation before the patching...
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LVCONVERT(8)						      System Manager's Manual						      LVCONVERT(8)

NAME
lvconvert - convert a logical volume from linear to mirror or snapshot SYNOPSIS
lvconvert -m|--mirrors Mirrors [--mirrorlog {disk|core}] [--corelog] [-R|--regionsize MirrorLogRegionSize] [-A|--alloc AllocationPolicy] [-b|--background] [-i|--interval Seconds] [-h|-?|--help] [-v|--verbose] [--version] LogicalVolume[Path] [PhysicalVolume[Path]...] lvconvert -s|--snapshot [-c|--chunksize ChunkSize] [-h|-?|--help] [-v|--verbose] [-Z|--zero y|n] [--version] OriginalLogicalVolume[Path] SnapshotLogicalVolume[Path] DESCRIPTION
lvconvert will change a linear logical volume to a mirror logical volume or to a snapshot of linear volume and vice versa. It is also used to add and remove disk logs from mirror devices. OPTIONS
See lvm for common options. Exactly one of --mirrors or --snapshot arguments required. -m, --mirrors Mirrors Specifies the degree of the mirror you wish to create. For example, "-m 1" would convert the original logical volume to a mirror volume with 2-sides; that is, a linear volume plus one copy. --mirrorlog {disk|core} Specifies the type of log to use. The default is disk, which is persistent and requires a small amount of storage space, usually on a separate device from the data being mirrored. Core may be useful for short-lived mirrors: It means the mirror is regenerated by copying the data from the first device again every time the device is activated - perhaps, for example, after every reboot. --corelog The optional argument "--corelog" is the same as specifying "--mirrorlog core". -R, --regionsize MirrorLogRegionSize A mirror is divided into regions of this size (in MB), and the mirror log uses this granularity to track which regions are in sync. -b, --background Run the daemon in the background. -i, --interval Seconds Report progress as a percentage at regular intervals. -s, --snapshot Create a snapshot from existing logical volume using another existing logical volume as its origin. -c, --chunksize ChunkSize Power of 2 chunk size for the snapshot logical volume between 4k and 512k. -Z, --zero y|n Controls zeroing of the first KB of data in the snapshot. If the volume is read-only the snapshot will not be zeroed. Examples "lvconvert -m1 vg00/lvol1" converts the linear logical volume "vg00/lvol1" to a two-way mirror logical volume. "lvconvert --mirrorlog core vg00/lvol1" converts a mirror with a disk log to a mirror with an in-memory log. "lvconvert --mirrorlog disk vg00/lvol1" converts a mirror with an in-memory log to a mirror with a disk log. "lvconvert -m0 vg00/lvol1" converts a mirror logical volume to a linear logical volume. "lvconvert -s vg00/lvol1 vg00/lvol2" converts logical volume "vg00/lvol2" to snapshot of original volume "vg00/lvol1" SEE ALSO
lvm(8), vgcreate(8), lvremove(8), lvrename(8), lvextend(8), lvreduce(8), lvdisplay(8), lvscan(8) Red Hat, Inc LVM TOOLS 2.02.44-cvs (02-17-09) LVCONVERT(8)
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