SVM - Fast Resync mirror volume

RAID 1 volumes (mirroring) can benefit from increased sync buffer size to 1M (2048 512 blocks). To experiment use metasync -r 2048 command. For permanent changes:

• On the Solaris 10 systems added the following line to /etc/system. set md_mirror:md_resync_bufsz = 2048
   
• For Solaris 9 edit the S95svm.sync file to include the "2048" buffer size.

• Tips and Tricks:

  By default the system will not boot without one more than half the total metadb replicas. I suggest you put extra copies of the metadb on some of your non-system disks. If you only have two disks (IE: the system disks) I suggest you add this entry to your /etc/system file:

  set md:mirrored_root_flag=1
  

  This will allow you to boot with only one metadb, if one of you disk drives fails.
  Also, you might want to add:

  set md_mirror:md_resync_bufsz = 2048
  

  to /etc/system as well. This greatly speeds up resyncs of failed mirror components by using 2 meg buffers instead of the default 128k. On one of our SunFire V215 machines, this increased the resync speed from 8-9 MB/second to 36-37 MB/second.
  The default maximum number of devices is 128. IE: creating a metadevice named "d129" will fail with an error. You can increase this by changing:

  nmd=128 
  

  to

  nmd=400
  

  in /kernel/drv/md.conf. This required a "boot -r" to take effect.