QSM vs VSM

[danielang]

Hi Guys,

I've two nodes of FAS2040 and is used as CIFS shares only. I would like to do a CIFS snapmirror to my DR site. Both site has a bandwidth of 2MB only. My questions are:

1) Should i use qtree snap mirror or volume snap mirror? what are the differences

2) One it is replicated to DR, what should i do in order for user to mount to the DR volume to access the files?

thansks in advance .. newbies here ..

[radek_kubka]

Hi and welcome ti the Community!

Bandwidth-wise, there is no difference between VSM (asynchronous) & QSM. Normally you would use the former for DR purposes, as syncing back is much easier in a fail-over / fail-back scenario.

Have a look at this doc (page 97) for a more thorough comparison between VSM & QSM:

http://now.netapp.com/NOW/knowledge/docs/ontap/rel733/pdfs/ontap/onlinebk.pdf

Regards,
Radek

[danielang]

Hi Radek,

Thanks, i've just a single CIFS share with multiple sub folder to make my life easier i will just configure VSM. Please advise if this logic is wrong?

also to make the DR copy writable, i would use snapmirror break and then snapmirror resync to resume back. what if i do not issue the break command and the the DR volume is read only my user can still access the CIFS share and copy file out without any write operation right?

[radek_kubka · Accepted solution]

Thanks, i've just a single CIFS share with multiple sub folder to make my life easier i will just configure VSM.

Sounds right to me.

also to make the DR copy writable, i would use snapmirror break and then snapmirror resync to resume back.

Yes, but if you actually make any changes to the DR copy, you would first reverse the direction of replication, resync any changes, break mirror again, then finally reverse the direction again.

what if i do not issue the break command and the the DR volume is read only my user can still access the CIFS share and copy file out without any write operation right?

Yes, everything will be visible in a read-only state (including any snapshots) - files can be drag & dropped to a r/w volume, or (if you have a licence) you can use FlexClone to create r/w 'thin' copy of the entire volume.