olbigtenor:
...
> lshw gives
>

>  *-sata
>                       description: SATA controller
>                       product: ASMedia Technology Inc.
>                       vendor: ASMedia Technology Inc.
>                       physical id: 0
>                       bus info: pci@0000:05:00.0
>                       logical name: scsi2
>                       logical name: scsi3
>                       logical name: scsi16
>                       logical name: scsi17
>                       version: 02
>                       width: 32 bits
>                       clock: 33MHz
>                       capabilities: sata pm msi pciexpress ahci_1.0
> bus_master cap_list rom emulated
>                       configuration: driver=ahci latency=0
>                       resources: irq:119 memory:fc982000-fc983fff
> memory:fc980000-fc981fff memory:fc900000-fc97ffff

>
> which drives are my raid-10 array
...

As you can see there are four drives here and the sata controller
is an AHCI one.

///

You havn't told us if your cd-drive is a SATA drive or not, it
could be USB attatched or be an older thing (though unlikely).
So I'm going to assume it is a SATA drive.

Is your cd-drive connected to the same controller as your
hard drives ?
If it is connected to some onboard raid controller, there might
be so that there is no driver for that controller and hence
no access to the cd-drive from Linux, depending on how that
controller is configured.

Sata is designed so that drives can hotplug to it.

Here you have to look in your system log.
The system logs as usually saved in /var/log, and
/etc/syslog.conf and /etc/syslog.conf.d/* decides which file
to append to for each kind of message to the logs.
Lock for lines beginning with kern. in your conf file(s) and
what action (eg. file name) is specifed. Especially if there
is a rule kernal.*, look into that file with "tail -f" to see
what's happening.

When I breafly disconnect a drive, I get this:
Aug 24 17:31:59 angelit kern.info kernel: [1793941.875169] ata4: SATA link down (SStatus 0 SControl 300)
and when connected again:
Aug 24 17:32:01 angelit kern.info kernel: [1793944.130344] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
Aug 24 17:32:01 angelit kern.info kernel: [1793944.133913] ata4.00: configured for UDMA/100

 If I disconnects it for longer times I get:
Aug 24 17:32:53 angelit kern.info kernel: [1793996.336163] ata4: SATA link down (SStatus 0 SControl 300)
Aug 24 17:32:59 angelit kern.info kernel: [1794001.651892] ata4: SATA link down (SStatus 0 SControl 300)
Aug 24 17:32:59 angelit kern.warn kernel: [1794001.651902] ata4: limiting SATA link speed to <unknown>
Aug 24 17:33:04 angelit kern.info kernel: [1794007.284149] ata4: SATA link down (SStatus 0 SControl 3F0)
Aug 24 17:33:04 angelit kern.warn kernel: [1794007.284158] ata4.00: disabled
Aug 24 17:33:04 angelit kern.info kernel: [1794007.284180] ata4.00: detaching (SCSI 3:0:0:0)
 and when reconnected:
Aug 24 17:33:07 angelit kern.info kernel: [1794010.551190] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
Aug 24 17:33:07 angelit kern.info kernel: [1794010.553462] ata4.00: ATAPI: ASUS     DRW-24F1ST   a, 1.00, max UDMA/100
Aug 24 17:33:07 angelit kern.info kernel: [1794010.554449] ata4.00: configured for UDMA/100
Aug 24 17:33:07 angelit kern.notice kernel: [1794010.555844] scsi 3:0:0:0: CD-ROM            ASUS     DRW-24F1ST   a   1.00 PQ: 0 ANSI: 5
Aug 24 17:33:08 angelit kern.info kernel: [1794010.594684] sr 3:0:0:0: [sr0] scsi3-mmc drive: 48x/48x writer dvd-ram cd/rw xa/form2 cdda tray
Aug 24 17:33:08 angelit kern.debug kernel: [1794010.594790] sr 3:0:0:0: Attached scsi CD-ROM sr0
Aug 24 17:33:08 angelit kern.notice kernel: [1794010.594832] sr 3:0:0:0: Attached scsi generic sg2 type 5

 As you can see, i have a mmc drive connected to scsi host 3, channel 
 0, id 0, lun 0, accessible as sr0 (actually /dev/scd0) or sg2, which
 can be verified by:
  # sg_map -i -x | grep cd
  /dev/sg2  3 0 0 0  5  /dev/scd0  ASUS      DRW-24F1ST   a    1.00
  #

So, look in the log for the kernel logs while connecting you cd-drive's
data cable (the smaller one, usually with a red flat cable) to
different connectors (on your motherboard or SATA-card), and see if
you can get similar results as me.

If no luck, try a different cable, same port as a hard drive, same
cable as a hard drive (your raid should survive, but you can fail/
remove the drive from your raid system beforehand) etc.

Regards,
/Karl Hammar