Date: Thu, 10 Jul 2008 08:55:17 -0700 (PDT) From: Juri Mianovich <juri_mian@yahoo.com> To: Alexandre Biancalana <biancalana@gmail.com>, Jeff Mohler <speedtoys.racing@gmail.com> Cc: freebsd-fs@freebsd.org Subject: Re: 24 TB UFS2 reality check ? Message-ID: <223496.96060.qm@web45607.mail.sp1.yahoo.com> In-Reply-To: <a969fbd10807091802r20880a9am241bf4c100d29f45@mail.gmail.com>
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Jeff,
--- On Wed, 7/9/08, Jeff Mohler <speedtoys.racing@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.
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