24 TB UFS2 reality check ?

[Juri Mianovich]

Jeff,


--- On Wed, 7/9/08, Jeff Mohler <speedtoys.racing at gmail.com> wrote:

> Lets see..a peak of maybe 25-30 random drive IOPS/sec at
> 15ms MINIMAL
> latency per IO (likely more like 35-40)..gonna be ugly.
> 
> Complicated by normal load IOPS..you could expect it all to
> simply
> "dissapear" for a day while it reconstructs.


Once again, thank you very much - your comments are very helpful.

So we've moved from "dangerous" (24 TB with no raid) to "inconvenient" (24 TB with raid 6).

Two final questions:

1. What would _you_ do with 24 1 TB disks and a 24 port 3ware card ?  Assume an i386, 4 GB machine, and that fsck is workable because of "newfs -i 131072"

2. What number should I ask my vendor (3ware) to do the rebuild calculations ?  You are talking about IOPS/s - I think I should ask them how many IOPS/s the card does when rebuilding a 24 disk raid-6 array, and then combine that with the IOPS/s I see in my normal workload.

How do you measure IOPS/s in FreeBSD on a running machine ?


And, of course, any other comments appreciated.

Thanks.