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Operating Systems Linux Red Hat Is overlapping two RAID5 arrays on same drives a bad idea ?? Post 302527701 by mark54g on Saturday 4th of June 2011 05:21:45 PM
Old 06-04-2011
Well, unless you are actually planning on using the xen functions, I would personally use the vanilla kernel.

The other options, I feel would be to use the 500GB drives in RAID 5 (chunk size should depend on the size of the majority of your files and the type of file system.

For the 1TB drives, a RAID 1E might make more sense. The issue is not only about the speed of the drives in optimal state, but how quickly you can recover from a failure before another read failure causes data loss. RAID 1/10/1E call for a simple copy, where RAID 5 and 6 usually call for an xor checksum.

With larger and larger drives, and the long time to get spares, a failure can easily go through more than one drive and cause data loss.

You may also want to consider using something like DRBD to another machine, instead of just amanda if your data is critical. Alternately, unison works well when the environment is mixed.
 

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metareplace(1M) 					  System Administration Commands					   metareplace(1M)

NAME
metareplace - enable or replace components of submirrors or RAID5 metadevices SYNOPSIS
/usr/sbin/metareplace -h /usr/sbin/metareplace [-s setname] -e mirror component /usr/sbin/metareplace [-s setname] mirror component-old component-new /usr/sbin/metareplace [-s setname] -e RAID component /usr/sbin/metareplace [-s setname] [-f] RAID component-old component-new DESCRIPTION
The metareplace command is used to enable or replace components (slices) within a submirror or a RAID5 metadevice. When you replace a component, the metareplace command automatically starts resyncing the new component with the rest of the metadevice. When the resync completes, the replaced component becomes readable and writable. If the failed component has been hot spare replaced, the hot spare is placed in the available state and made available for other hot spare replacements. Note that the new component must be large enough to replace the old component. A component may be in one of several states. The Last Erred and the Maintenance states require action. Always replace components in the Maintenance state first, followed by a resync and validation of data. After components requiring maintenance are fixed, validated, and resynced, components in the Last Erred state should be replaced. To avoid data loss, it is always best to back up all data before replacing Last Erred devices. OPTIONS
Root privileges are required for all of the following options except -h. -e Transitions the state of component to the available state and resyncs the failed component. If the failed component has been hot spare replaced, the hot spare is placed in the available state and made available for other hot spare replace- ments. This command is useful when a component fails due to human error (for example, accidentally turning off a disk), or because the component was physically replaced. In this case, the replacement component must be partitioned to match the disk being replaced before running the metareplace command. -f Forces the replacement of an errored component of a metadevice in which multiple components are in error. The component determined by the metastat display to be in the ``Maintenance'' state must be replaced first. This option may cause data to be fabricated since multiple components are in error. -h Display help message. -s setname Specifies the name of the diskset on which metareplace will work. Using the -s option will cause the command to perform its administrative function within the specified diskset. Without this option, the command will perform its function on local metadevices. mirror The metadevice name of the mirror. component The logical name for the physical slice (partition) on a disk drive, such as /dev/dsk/c0t0d0s2. component-old The physical slice that is being replaced. component-new The physical slice that is replacing component-old. RAID The metadevice name of the RAID5 device. EXAMPLES
Example 1 Recovering from Error Condition in RAID5 Metadevice This example shows how to recover when a single component in a RAID5 metadevice is errored. # metareplace d10 c3t0d0s2 c5t0d0s2 In this example, a RAID5 metadevice d10 has an errored component, c3t0d0s2, replaced by a new component, c5t0d0s2. Example 2 Use of -e After Physical Disk Replacement This example shows the use of the -e option after a physical disk in a submirror (a submirror of mirror mymirror1, in this case) has been replaced. # metareplace -e mymirror1 c1t4d0s2 Note: The replacement disk must be partitioned to match the disk it is replacing before running the metareplace command. EXIT STATUS
The following exit values are returned: 0 Successful completion. >0 An error occurred. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWmdu | +-----------------------------+-----------------------------+ |Interface Stability |Stable | +-----------------------------+-----------------------------+ SEE ALSO
mdmonitord(1M), metaclear(1M), metadb(1M), metadetach(1M), metahs(1M), metainit(1M), metaoffline(1M), metaonline(1M), metaparam(1M), metarecover(1M), metarename(1M), metaroot(1M), metaset(1M), metassist(1M), metastat(1M), metasync(1M), metattach(1M), md.tab(4), md.cf(4), mddb.cf(4), md.tab(4), attributes(5), md(7D) SunOS 5.11 26 Mar 2006 metareplace(1M)
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