topic Re: raid mirror question in Disk Enclosures

raid mirror question

Simon Hyams — Fri, 27 Aug 2004 08:33:53 GMT

in a raid1 mirror, is one disk active and one passive? i.e. are they as equal as each other or is one "boss"?
in either case, if i take out the "slave" disk from a mirrored pair, and put it in a an identical server without breaking the mirror, will it still boot to that disk. i know if you use the "master" disk it will just say "other disk broken - insert new disk or fail it?" and you can still boot to it.

Re: raid mirror question

JohnWRuffo — Fri, 27 Aug 2004 10:45:56 GMT

Simon:

Are you using hardware or software RIAD?

Generally speaking you do not want to migrate just one disk of a mirror to a new server. You want to migrate the mirror set.

If you can give more detail to the question I have above, we can give you a much better answer.

Re: raid mirror question

Steven Clementi — Fri, 27 Aug 2004 12:48:41 GMT

If you are using a Proliant Server with a Smart Array controller, then you can take EITHER the first disk OR the second disk and put it into another server and boot from it.

The key is, you need to put the drive in the same slot it was in originally.... example...

in a DL360, there is Drive Bay 0 and Drive Bay 1. If you take the drive out of Drive Bay 1, you need to put the drive BACK into Drive Bay one on the new DL360.

This is a quick and easy way to replicate a system, or have a cold backup on a shelf. Once you split the disks, make sure you re-populate the the second disk after the server boots so that the Smart Array can rebuild the mirror.

In RAID 1, there really isn't a master/slave. The Smart Array controller write to BOTH disks at the same time, but can read different data from each individual disk, which is why RAID 1 is better for read intensive applications.

Once you remove the drive, you have already broken the mirror. Let the server boot and insert the second drive AFTER your into the OS and you confirm everything is ok.

Steven