Hi,

In short the answer is yes. Take Oracle as an example. Oracle does dependent writes, meaning Oracle will not ack write B unless it received an ack from write A. Therefore the snapshot you create will be one three possibilities: a) A and B are present; 2. A is present but not B, 3) Both A and B are not present.

If your database is spread across multiple volumes or controllers, you can use NetApp Data ONTAP CG APIs (cg-start and cg-commit) to achieve a crash consistent image. Hope this helps.

Srinath

Bear in mind NVRAM is not a write cache - it is a journal.

This is pretty old, but still good reading about how NVRAM works:

http://www.netapp.com/us/library/technical-reports/wp-3001.html

Page 10 says:

Using NVRAM to store a log of uncommitted requests is very different from using NVRAM as a disk cache, as some UNIX products do [Lyon89]. When NVRAM is used at the disk layer, it may contain data that is critical to file system consistency. If the NVRAM fails, the file system may become inconsistent in ways that fsck cannot correct.
WAFL uses NVRAM as a file system journal, not as a cache of disk blocks that need be changed on the drives. As such, WAFL use of NVRAM space is extremely efficient. For example, a request for a file system to create a file can be described in just a few hundred bytes of information, where as the actual operation of creating a file on disks might involve changing a dozen blocks of information or more. Because WAFL uses NVRAM as a journal of operations that need to be performed on the drives, rather than the result of the operations themselves, thousands of operations can be journaled in a typical storage appliance NVRAM log.

Hope it helps.

Regards,
Radek

This particular bit I believe is very relevant to your question:

When snapshot is taken, new CP is always created.

You may play with it by scheduling a snapshot & then issuing following command:

sysstat –x 1

Look for "S" in "CP ty" column.

Regards,
Radek