# How to tell if I can hot swap a disk?



## littlesandra88 (Jul 15, 2013)

Hello 

After having done a ZFS scrub, I see


```
tank3                   DEGRADED     0     0     0
...
	  raidz2-3              DEGRADED     0     0     0
	    da18                ONLINE       0     0     0
	    da19                ONLINE       0     0     0
	    641984491336313519  UNAVAIL      0     0     0  was /dev/da20
	    da21                ONLINE       0     0     0
	    da22                ONLINE       0     0     0
	    da23                ONLINE       0     0     0
```

so I guess I have a dead disk?

While the host is running I would be temped to


```
zpool offline tank3 da20
<physically replace the disk>
zpool replace tank3 da20
```

but since the disk devices are called daX and not adaX, I don't know if there are hot swappable?


```
# atacontrol 
atacontrol: 
ATA_CAM option is enabled in kernel.
Please use camcontrol instead.

# camcontrol devlist
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 10 lun 0 (pass0,da0)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 11 lun 0 (pass1,da1)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 12 lun 0 (pass2,da2)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 13 lun 0 (pass3,da3)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 14 lun 0 (pass4,da4)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 15 lun 0 (pass5,da5)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 16 lun 0 (pass6,da6)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 17 lun 0 (pass7,da7)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 18 lun 0 (pass8,da8)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 19 lun 0 (pass9,da9)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 20 lun 0 (pass10,da10)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 21 lun 0 (pass11,da11)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 22 lun 0 (pass12,da12)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 23 lun 0 (pass13,da13)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 24 lun 0 (pass14,da14)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 25 lun 0 (pass15,da15)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 26 lun 0 (pass16,da16)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 27 lun 0 (pass17,da17)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 28 lun 0 (pass18,da18)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 29 lun 0 (pass19,da19)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 30 lun 0 (pass20,da20)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 31 lun 0 (pass21,da21)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 32 lun 0 (pass22,da22)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 33 lun 0 (pass23,da23)
<LSI CORP SAS2X36 0717>            at scbus0 target 34 lun 0 (ses0,pass24)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 35 lun 0 (pass25,da24)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 36 lun 0 (pass26,da25)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 37 lun 0 (pass27,da26)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 38 lun 0 (pass28,da27)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 39 lun 0 (pass29,da28)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 40 lun 0 (pass30,da29)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 41 lun 0 (pass31,da30)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 42 lun 0 (pass32,da31)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 43 lun 0 (pass33,da32)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 44 lun 0 (pass34,da33)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 45 lun 0 (pass35,da34)
<ATA ST3000DM001-1CH1 CC24>        at scbus0 target 46 lun 0 (pass36,da35)
<LSI CORP SAS2X28 0717>            at scbus0 target 47 lun 0 (ses1,pass37)
<SATADOM i100 Ultra rs2.a000>      at scbus5 target 1 lun 0 (ada0,pass38)
```

How do I know if hot swap is possible on my Seagate Constellation CS ST3000NC002 SATA drives?

I am using FreeBSD 9.1.

Hugs,
Sandra


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## mav@ (Jul 15, 2013)

It is question about the HBA, not about the disk. daX just means that it is SCSI (at least shown as such to the OS). What is behind it, is handled by the HBA driver and its firmware. SAS controllers, probably used here should probably support hot-plug.


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## cpm@ (Jul 17, 2013)

@mav@ makes a good point. The SAS HBA has functions like hot swap so if you read the HDD data sheet you can find out if it's supported. Well, it seems that it has support for hot-plug operation (per SATA Rev. 3.0 Specifications), therefore it should work fine.


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## littlesandra88 (Jul 17, 2013)

Thanks a lot. Indeed it worked


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