Re: snapvault slow performance

On 26 Jan 2007 08:56:33 -0800, "Raju Mahala" <rajumahala@xxxxxxxxx>
wrote:

Hi all,
I face performance issue on snapvault for some specific volumes.
First I explain my configuration. Around 10primary filers are
configured for snapvault on single R200 and used data size is around
45TB. Now almost all volumes are taking place overnight for changed
data but on some volumes it takes more than 24hr. If I compare those
volumes with others then I found that no. of files on these volumes are

more and average file size is also very less. But I feel snapvault
works at block level so these factors should not affect.
So can you suggest where should I hit or how to findout the reason.


Thanks & Regards,
Raju Mahala
Storage & Backup Admin
STMicroelectronics Pvt. Ltd.
INDIA


Snapvault works at the qtree level, so it's a logical seperation from
the physical blocks.

Even though it only transfers changed blocks it still has to map files
to blocks to determine which blocks/files in a qtree changed. This
mapping can be very resource intensive and take a long time if the
file count is extremely high.

If you snapmirror at the volume level (no snapvault available at the
volume level) then you will get pure block transfers with no mapping.
But the benefit of snapvault is the scheduling and snapshot
coalescing, neither of which snapmirror has (qtree or volume level).

~F
.