45 messages in org.freebsd.freebsd-fsRe: Areca vs. ZFS performance testing.| From | Sent On | Attachments |
|---|---|---|
| Jeremy Chadwick | Oct 30, 2008 8:31 pm | |
| Danny Carroll | Oct 30, 2008 9:07 pm | |
| Jeremy Chadwick | Oct 30, 2008 9:33 pm | |
| Andrew Snow | Oct 30, 2008 9:43 pm | |
| Danny Carroll | Oct 30, 2008 9:47 pm | |
| Danny Carroll | Oct 30, 2008 9:49 pm | |
| Danny Carroll | Oct 30, 2008 9:54 pm | |
| Simun Mikecin | Oct 31, 2008 2:20 am | |
| Simun Mikecin | Oct 31, 2008 4:56 am | |
| Peter Schuller | Nov 2, 2008 7:08 am | |
| Simun Mikecin | Nov 3, 2008 12:31 am | |
| Dieter | Nov 12, 2008 2:57 pm | |
| Danny Carroll | Nov 12, 2008 9:46 pm | |
| Jeremy Chadwick | Nov 12, 2008 11:42 pm | |
| Willem Jan Withagen | Nov 13, 2008 12:32 am | |
| Danny Carroll | Nov 13, 2008 3:09 am | |
| Danny Carroll | Nov 13, 2008 5:58 am | |
| Nikolay Denev | Nov 13, 2008 7:05 am | |
| Scott Long | Nov 13, 2008 8:49 am | |
| Danny Carroll | Nov 13, 2008 12:46 pm | |
| Danny Carroll | Nov 13, 2008 12:59 pm | |
| Eirik Øverby | Nov 16, 2008 12:26 pm | |
| Danny Carroll | Nov 16, 2008 7:15 pm | |
| Matt Simerson | Nov 16, 2008 10:06 pm | |
| Jeremy Chadwick | Nov 16, 2008 11:07 pm | |
| Wes Morgan | Nov 17, 2008 3:26 am | |
| Danny Carroll | Nov 17, 2008 3:42 am | |
| Matt Simerson | Nov 17, 2008 1:04 pm | |
| Matt Simerson | Nov 17, 2008 2:07 pm | |
| Danny Carroll | Nov 17, 2008 3:45 pm | |
| Jan Mikkelsen | Dec 2, 2008 2:38 am | |
| Wes Morgan | Dec 2, 2008 4:04 am | |
| Danny Carroll | Jan 7, 2009 4:33 pm | |
| Zaphod Beeblebrox | Jan 7, 2009 11:40 pm | |
| Koen Smits | Jan 7, 2009 11:48 pm | |
| Nikolay Denev | Jan 8, 2009 1:19 am | |
| Danny Carroll | Jan 8, 2009 6:29 pm | |
| Koen Smits | Jan 9, 2009 12:46 am | |
| Danny Carroll | Jan 9, 2009 1:02 am | |
| Koen Smits | Jan 9, 2009 7:57 am | |
| Andrew Snow | Jan 9, 2009 6:38 pm | |
| Danny Carroll | Jan 9, 2009 8:58 pm | |
| Danny Carroll | Jan 20, 2009 10:40 pm | |
| Koen Smits | Jan 21, 2009 1:15 am | |
| Danny Carroll | Jan 21, 2009 5:14 am |
| Subject: | Re: Areca vs. ZFS performance testing. | |
|---|---|---|
| From: | Danny Carroll (fb...@dannysplace.net) | |
| Date: | Nov 13, 2008 12:59:10 pm | |
| List: | org.freebsd.freebsd-fs | |
Scott Long wrote:
The Areca controller likely doesn't buffer/cache for disks in JBOD mode, as others in this thread have stated. Without buffering, simple disk controllers will almost always be faster than accelerated raid controllers because the accelerated controllers add more latency between the host and the disk. A simple controller will directly funnel data from the host to the disk as soon as it receives a command. An accelerated controller, however, has a CPU and a mini-OS on it that has to schedule the work coming from the host and handle its own tasks and interrupts. This adds latency that quickly adds up under benchmarks. Your numbers clearly demonstrate this.
That's nice to know. I'm not sure it tells us why the Non-Cached writes were about 8% faster though. The other thing about the "NoWriteCache" test I performed that I neglected to mention yesterday is that I actually panic'd the box (running out of memory). This was the first time I have had that happen with ZFS even though in previous testing (with cache enabled) I punished the box for a lot longer.
Perhaps the ZFS caching took over where the disk caching left off? Could that explain why I did not see a negative difference in the numbers between Cache enabled and Cache disabled?
One of the questions I wanted to answer for myself was just this: "Does a battery-backed cache on an Areca card protect me when I am in JBOD mode." If the Areca does not buffer/cache in JBOD mode then that means the answer is no.
-D
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