I'm not using Xsan, but I'm using hardware I'm hoping (praying) someone here has in-depth experience administering.
I don't want to have to reformat the RAID and I don't want to lose data because the organization will suffer extended downtime. I've used ChronoSync to back up the entire RAID twice onto two 2TB USB drives. Each one took over two days to complete, so if I mess this up and cause data loss by merging slices, it'll take at least that long to get the data back on the system.
These and Apple's documentation are a few of the many different sources of info on this topic I've sought.
I inherited administration responsibilities for an xServe RAID using the latest firmware (1.5.1).
The xServe is an intel xeon dual 2 GHz, running Mac OS X Server 10.6.8
The RAID had six (sigh) drives in the left controller. None in the right.
When I became admin, one of these six was dead. So I went on eBay and got three refurb ADM's.
--one to replace the dead drive.
--another to expand the RAID 5 to a full seven drives. (from 2.5T to 2.73T)
--a third to put on the shelf as a spare.
I am using RAID Admin utility 1.5.2b3.
The replacement drive rebuilt beautifully. Happy 6 drive RAID.
I put in the 7th drive and expanded. It took several days.
I'm at the point of "merging" slices that gives everyone pause about losing data.
Can Intel Macs can expand the file system with this slice-merging function without data loss whereas Power PC Macs cannot?
Next, my RAID as I inherited it was one slice. That is to say, one volume. One partition. In RAID Admin under "Arrays and Drives" all the little drives display a . They did when the RAID was degraded to 5 drives. They did when I added the 6th drive replacement. They do now, having used the Expansion function under "Advanced" to add the 7th drive.
So, next question. WAS IT EVER SLICED?
That seems to be a deal-breaker for merging slices without data loss.
For this, I looked in RAID Admin to my Events tab which dates all the way back to 2008.
I see exactly zero mentions of slicing anywhere.