another data point for the group. the previous scan was run on our busiest filer (an fas270); below is the impact of doing a scan on our largest user data filer.
this filer is an fas270 with one ds14. there are 11 disks in the raid group (and aggregate). the volume is only 3-4 months old, but storage utilization vascillates wildly on this puppy but it usually operates above 95% and has run out of space several times in its young life. we are not snapmirroring. i think we are currently using 995gb (.97tb) on the volume including snap, but someone should check my calculation (df below).
i started the scan at the beginning of lunchtime, when the filer happened to be nearly quiescent. it took 54 minutes. it killed my cache but only sucked up 7-12% of the cpu.
i imagine a low fragmentation condition would make a scan less taxing.
...lori
/vol/vol1/ 1132462080KB 917995432KB 214466648KB 81% /vol/vol1/ /vol/vol1/.snapshot 125829120KB 153743936KB 0KB 122% /vol/vol1/.snap shot
cartman*> sysstat 1 CPU NFS CIFS HTTP Net kB/s Disk kB/s Tape kB/s Cache in out read write read write age 1% 0 0 0 0 0 0 0 0 0 >60 1% 0 0 0 0 0 0 0 0 0 >60 1% 0 0 0 0 0 0 0 0 0 >60 1% 0 0 0 0 0 0 0 0 0 >60 1% 0 0 0 0 0 0 0 0 0 >60 4% 0 0 0 0 0 607 563 0 0 >60
cartman*> wafl scan measure_layout vol1 cartman*> Wed Mar 8 12:15:05 PST [wafl.scan.start:info]: Starting WAFL layout measurement on volume vol1.
cartman*> sysstat 1 CPU NFS CIFS HTTP Net kB/s Disk kB/s Tape kB/s Cache in out read write read write age 8% 0 0 0 0 0 583 0 0 0 15 10% 0 0 0 0 0 1168 572 0 0 15 7% 0 0 0 0 0 636 0 0 0 15 8% 0 0 0 0 0 648 0 0 0 15 8% 0 0 0 0 0 632 0 0 0 15 8% 0 0 0 0 0 660 0 0 0 15 7% 0 0 0 0 0 636 0 0 0 15 9% 0 0 0 0 0 696 0 0 0 15 8% 0 0 0 0 0 696 0 0 0 15 12% 0 0 0 0 0 844 0 0 0 15 7% 0 0 0 0 0 668 0 0 0 16
CPU NFS CIFS HTTP Net kB/s Disk kB/s Tape kB/s Cache in out read write read write age 7% 0 0 0 0 0 592 0 0 0 4 8% 0 0 0 1 0 736 0 0 0 4 11% 0 0 0 0 0 756 0 0 0 4 10% 0 0 0 0 0 864 0 0 0 4 11% 0 0 0 0 0 920 0 0 0 4 8% 0 0 0 0 0 644 0 0 0 4
cartman*> Wed Mar 8 13:09:00 PST [wafl.scan.layout.advise:info]: WAFL layout ratio for volume vol1 is 1.22. A ratio of 1 is optimal. Based on your free space, 3.94 is expected.