I've been running for a couple of years with a NetApp Disk Shelf 4246 (with IOM6 modules) with a fair amount of success on my Areca 1883IX-16 controller. Recently, I had a catastrophic loss of my RAID 6 (200 TB) due to a power surge caused by a table saw in my garage.
Skip to the next paragraph if you don't want the details (not relevant to the question). The surge went through both UPSs, knocked out (powered down) two drives before I realized it (spaced a few minutes apart), then a third drive got knocked out marking the array offline. Because it was not immediately offline, it went into degraded mode with two drives failed... when I powered it back up, it was happy enough, all the drives were fine, I started a rebuild process... then another drive started going intermittent (timeout errors). Managed to rebuild eventually (and trashed the intermittent drive), but something during the process blew up my ZFS FS... and it's all read-only now (freezes the kernel if you attempt to mount it read/write)
Because of this, I decided to up my ante and move to a RAID 61 (two RAID 6 arrays mirrored). I bought a second enclosure (another DS4246) and hooked it up via SAS connector, added a bunch of drives, and powered up my system.
Both shelves show good link lights on all connectors, communication looks appropriate to me (same cable config as what's been working for the last two years), I set the ID of the second shelf to "10" (with the first shelf being "00"). When the system was later powered on (after setting the ID and power-cycling to make the config stick)... the Areca controller couldn't see the drives in the 2nd enclosure. It could see the enclosure itself, and I could tell the card to "identify" it (flashing all access lights on the enclosure), which worked... but no drives were detected.
I then started trouble-shooting...
ASCII-art cable drawing:
Skip to the next paragraph if you don't want the details (not relevant to the question). The surge went through both UPSs, knocked out (powered down) two drives before I realized it (spaced a few minutes apart), then a third drive got knocked out marking the array offline. Because it was not immediately offline, it went into degraded mode with two drives failed... when I powered it back up, it was happy enough, all the drives were fine, I started a rebuild process... then another drive started going intermittent (timeout errors). Managed to rebuild eventually (and trashed the intermittent drive), but something during the process blew up my ZFS FS... and it's all read-only now (freezes the kernel if you attempt to mount it read/write)
Because of this, I decided to up my ante and move to a RAID 61 (two RAID 6 arrays mirrored). I bought a second enclosure (another DS4246) and hooked it up via SAS connector, added a bunch of drives, and powered up my system.
Both shelves show good link lights on all connectors, communication looks appropriate to me (same cable config as what's been working for the last two years), I set the ID of the second shelf to "10" (with the first shelf being "00"). When the system was later powered on (after setting the ID and power-cycling to make the config stick)... the Areca controller couldn't see the drives in the 2nd enclosure. It could see the enclosure itself, and I could tell the card to "identify" it (flashing all access lights on the enclosure), which worked... but no drives were detected.
I then started trouble-shooting...
- I moved one drive from the lower shelf to the upper shelf - controller detects the new drive fine, drive appears functional
- I tried a known-working drive from the old shelf on the new shelf - not detected.
- I swapped out IOM6 boards (both with the known-working old shelf, and with another tray-less shelf I have for spare parts) - same results, no drives detected.
ASCII-art cable drawing:
Code:
+-------------+
| Controller ||
+------------|+
\
+--------------|+
| IOM6 board | || \
+------------|--+ \
\ > Old Shelf (ID 00)
+--------------|+ /
| IOM6 board | || /
+------------|--+
\
+--------------|+
| IOM6 board | || \
+------------|--+ \
\ > New Shelf (ID 10)
+--------------|+ /
| IOM6 board o || /
+---------------+
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