ad0: WARNING - removed from configuration (atacontrol and gmirror relationship?)

[firmdog at gmail.com]

This just happened on my server:

Nov 22 03:21:11 sockeye kernel: ad0: TIMEOUT - WRITE_DMA retrying (2 retries
left) LBA=28892960
Nov 22 03:21:11 sockeye kernel: ad0: WARNING - removed from configuration
Nov 22 03:21:11 sockeye kernel: GEOM_MIRROR: Device gm0s1: provider ad0
disconnected.
Nov 22 03:21:11 sockeye kernel: GEOM_MIRROR: Request failed (error=6).
ad0[WRITE(offset=13881704448, length=12288)]
Nov 22 03:21:11 sockeye kernel: GEOM_MIRROR: Request failed (error=6).
ad0[WRITE(offset=14795718656, length=2048)]
Nov 22 03:21:11 sockeye kernel: GEOM_MIRROR: Request failed (error=6).
ad0[WRITE(offset=770891776, length=16384)]
Nov 22 03:21:11 sockeye kernel: ata0-master: FAILURE - WRITE_DMA timed out
Nov 22 03:21:11 sockeye kernel: GEOM_MIRROR: Request failed (error=5).
ad0[WRITE(offset=14793195520, length=2048)]

Now the ad0 Master drive no longer exists:

-su-2.05b$ sudo atacontrol list
ATA channel 0:
    Master:      no device present
    Slave:  acd0 <SONY CD-ROM CDU5212/5YS1> ATA/ATAPI revision 5
ATA channel 1:
    Master:  ad2 <WDC WD800JB-00JJA0/05.01C05> ATA/ATAPI revision 6
    Slave:   ad3 <WDC WD400BB-75FRA0/77.07W77> ATA/ATAPI revision 6


What is the relationship between atacontrol and gmirror?


Why was the device removed completely?


Can I simply do this?  (want to be sure as this box is remote)

gmirror forget data

atacontrol attach ata0

gmirror insert data ad0