writes to ZFS objects have significant data and meta-data implications, based
on the zfs copy-on write implementation ... as data is written into a file
object, for example, this update must eventually be written to a new location
on physical disk, and all of the meta-data (from the uberblock
Bill Moloney wrote:
for example, doing sequential 1MB writes to a
previously written) zvol (simple catenation of 5
FC drives in a JBOD) and writing 2GB of data induced
more than 4GB of IO to the drives (with smaller write
sizes this ratio gets progressively worse)
How did you measure this?
Hello Bart,
Wednesday, May 16, 2007, 6:07:36 PM, you wrote:
BS Bill Moloney wrote:
for example, doing sequential 1MB writes to a
previously written) zvol (simple catenation of 5
FC drives in a JBOD) and writing 2GB of data induced
more than 4GB of IO to the drives (with smaller write
I think it's also important to note _how_ one measure performance
(which is black magic at the best of times).
I personally like to see averages since doing #iostat -xnz 10 doesn't
tell me anything really. Since zfs likes to bundle and flush I want
my (very expensive ;) Sun storage to give me
I've noticed a similar behavior in my writes. ZFS seems to write in bursts of
around 5 seconds. I assume it's just something to do with caching? I was
watching the drive lights on the T2000s with 3 disk raidz and the disks all
blink a couple seconds then are solid for a few seconds.
Is this
On Fri, 2007-05-11 at 09:00 -0700, lonny wrote:
I've noticed a similar behavior in my writes. ZFS seems to write in bursts of
around 5 seconds. I assume it's just something to do with caching?
Yep - the ZFS equivalent of fsflush. Runs more often so the pipes don't
get as clogged. We've had
On May 11, 2007, at 9:09 AM, Bob Netherton wrote:
**On Fri, 2007-05-11 at 09:00 -0700, lonny wrote:
**I've noticed a similar behavior in my writes. ZFS seems to write in bursts of
** around 5 seconds. I assume it's just something to do with caching?
^Yep - the ZFS equivalent of fsflush. Runs
lonny wrote:
On May 11, 2007, at 9:09 AM, Bob Netherton wrote:
**On Fri, 2007-05-11 at 09:00 -0700, lonny wrote:
**I've noticed a similar behavior in my writes. ZFS seems to write in bursts of
** around 5 seconds. I assume it's just something to do with caching?
^Yep - the ZFS equivalent of
