2011-09-14 08:22 AM
We have been having a Filer issue whenever we do any sort of large data copy on our filer. We have a FAS2050. We have noticed this during Exchange Snapshots and whenever we migrate a VM's storage to another datastore. We see 100% CPU utilization on the Filer as soon as we start the migration. The base average on the CPU prior to the migration is 25-30%. The datastores are iSCSI LUNS and not NFS. It doesn't matter how much data is copied it happens for the smallest amount. You definitely can notice a difference in performance on other VM's during this migration.
We do have a ticket open but they haven't found anything yet. Initially they said our filer is overloaded but how can it be overloaded if the CPU is only using 25-30%? We never had this problem with an HP EVA.
2011-09-14 01:29 PM
Hi and welcome to the Community!
Storage VMotion is quite intensive sequential read operation, which in turn requires a lot of CPU power on NetApp. WAFL is fragmented almost 'by definition', which is fine for random workloads. For sequential ones, a complex read-ahead caching algorithm is used.
You can try improving things by checking & possibly reducing fragmentation via reallocate command. Also, if your ONTAP version is lower than 7.3, I recommend upgrading it, as 7.3.x is more efficient with sequential reads.
Finally, FAS2050 CPU is really a slow one, I am afraid: