scsi and ata entries for same hard drive under /dev/disk/by-id

Posted by John Dibling on Server Fault See other posts from Server Fault or by John Dibling
Published on 2013-08-31T21:16:24Z Indexed on 2014/06/05 15:27 UTC
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linux

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zfs

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sata

I am trying to set up a ZFS pool using 4 bare drives which I have attached to my Ubuntu system via a SATA hot swap backplane.

These are Hitachi SATA drives. When I list the contents of /dev/disk/by-id, I see two entries for each drive:

root@scorpius:/dev/disk/by-id# ls | grep Hitachi
ata-Hitachi_HDS5C3030ALA630_MJ1323YNG0ZJ7C
ata-Hitachi_HDS5C3030ALA630_MJ1323YNG1064C
ata-Hitachi_HDS5C3030ALA630_MJ1323YNG190AC
ata-Hitachi_HDS5C3030ALA630_MJ1323YNG1DGPC
scsi-SATA_Hitachi_HDS5C30_MJ1323YNG0ZJ7C
scsi-SATA_Hitachi_HDS5C30_MJ1323YNG1064C
scsi-SATA_Hitachi_HDS5C30_MJ1323YNG190AC
scsi-SATA_Hitachi_HDS5C30_MJ1323YNG1DGPC

I know these are the same drives because I wrote down the serial numbers, and all the other drives in this system are either Seagate or WD. The serial number for the first one, for example, is YNG0ZJ7C.

Why are there two entries here for each drive? More to the point, when I create my ZFS pool which one should I use; the scsi- one or the ata- one?

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