Daniel Rock wrote:
Richard Elling - PAE schrieb:
The big question, though, is "10% of what?" User CPU? iops?
Maybe something like the "slow" parameter of VxVM?
slow[=iodelay]
Reduces toe system performance impact of copy
operations. Such operations are usually per-
formed on small regions of the volume (nor-
mally from 16 kilobytes to 128 kilobytes).
This option inserts a delay between the
recovery of each such region . A specific
delay can be specified with iodelay as a
number of milliseconds; otherwise, a default
is chosen (normally 250 milliseconds).
For modern machines, which *should* be the design point, the channel
bandwidth is underutilized, so why not use it?
NB. At 4 128kByte iops per second, it would take 11 days and 8 hours
to resilver a single 500 GByte drive -- feeling lucky? In the bad old
days when disks were small, and the systems were slow, this made some
sense. The better approach is for the file system to do what it needs
to do as efficiently as possible, which is the current state of ZFS.
-- richard
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