eSATA RAID options for TowerRAID TR8M6G

[AidenShaw]

Per AJA Test (disk whack 1 GB file):

106.2 MB/s write
4083.2 MB/s read

This is from a 4 x 4 TB mirrored pair Zpool inside '09 MacPro; Sata II speeds of course. Writes not so good, but reads are. Good enough for my uses and cheap.

I think that your reads are coming from cache - SATA II theoretical max would be about 1200 MB/s.

 

[msh]

I think that your reads are coming from cache - SATA II theoretical max would be about 1200 MB/s.

Correct, obviously. ZFS on my 32GB system makes quite good use of cache for reads. Writes are another story. I do need to look at some of the parameters for tuning ZFS for better writes including possibly implementing an SSD for temporary cache.

 

[msh]

Per AJA Test (disk whack 1 GB file):

106.2 MB/s write
4083.2 MB/s read

This is from a 4 x 4 TB mirrored pair Zpool inside '09 MacPro; Sata II speeds of course. Writes not so good, but reads are. Good enough for my uses and cheap.

Aiden, let me amend this post. I am getting very good write speeds* using Open ZFS 1.3.1. I didn't realize the metric I had posted above was from a newly installed OpenZFS v 1.5.2 which, as I have discovered, doesn't work well on my machine. Because of this I have reverted back to 1.3.1. I know it may not be wise to depend on unofficially supported software like OpenZFS but it runs really well (on the right version of course) and the protection and handling of data appears to be unmatched by anything else.

*approx. 200 MB/s on a RaidZ 5 disk single parity pool via Sata II through the Firmtek card and eSata out to the Sans Digital Tower. This was the speed backing up a 3.72TB media pool. Note that the Firmtek port multiplication eSata chain is a bit slower than internal MacPro Sata II - PM overhead I assume.