When using Access Appliance as secondary storage for FlashArray volume snapshots, it is recommended to mount the NFS share with the following options for better performance and minimize data loss.
- sync – data is flushed to disks on server instead of keeping data in the client or server caches. This option should be specified when exporting on Access to minimize data loss in case of failure.
- nfsvers=3 - it was observed that the performance when utilizing NFS version 3 is better when compared to the NFS version 4 protocol.
- rsize=1048576 and wsize=1048576 – the best performance was observed when setting the read and write size values to 1 MB. This value specifies the number of bytes that NFS utilizes to read and write files on the NFS server.
Since multiple FlashArray can store snapshots on a single Access Appliance, it is recommended as a best practice to use a separate NFS share as the offload target for each FlashArray for segregation and ease of management. Snapshots from different FlashArray can be seen in each FlashArray utilizing the same share. For instance, snapshots taken from two FlashArray can be seen in both FlashArray. Additionally, those snapshots can only be removed by the FlashArray where the protection group resides or where the snapshot was created. Furthermore, it is recommended to use the NFS share solely for FlashArray snapshots and not for other file sharing purposes. Better performance was also observed when utilizing different file systems for each share.
The optimum frequency to conduct “Snap to NFS” is generally dependent on size of the data, the network bandwidth, and system resources on the FlashArray. However, per Snap to NFS Overview and Administration documentation, it is recommended to offload data not more than once or twice a day.