2010-03-04 03:47 AM
When i'm trying to add spare disks into aggr, the system said "
WARNING! With disks added, the aggregate will be too big to revert to Data ONTAP 7.2.
Are you sure you want to continue with aggr add?"
So, from my understanding, the message came out is because 7.3 allows for larger aggr than 7.2. This message is just letting me know that i'm exceeding the aggr limit for 7.2, so i won't be able to revert to ONTAP 7.2 version.
It's that correct? By the way, i'm using 7.3.2P4 now.
So, there should be no issues if i adding the disks. right?
Actually, what are the normal practices for this? If anything goes wrong, corrupted or whatever… how could i revert back to the original state instead of install new ONTAP?
It looks like i need to have many aggregate creations inside of per controller. If this happened, is there any issue in term of performance impact?
2010-03-04 08:49 AM
There are no issues as long as you don't ever want to revert back to 7.2. The good news is that reverting ONTAP releases is pretty rare so you should be safe there.
It's more of an issue if you just upgraded to 7.3 and think you might hit some critical issue. But 7.3.2 is a pretty solid release, IMHO. If you ever HAD to revert you would have to destroy that aggr first.
But, again, this is a pretty unusual thing in practice, especially when you're sitting on a GD release.
I tend to avoid having lots of aggregates if at all possible. I prefer a few large aggregates as this gives me the most flexibility as well as best utilization and best performance at the disk level.
The main reasons to have multiple aggregates are:
1. Space. There are aggregate limits so if I need more space than 1 aggr can hold, I need more than 1 aggr.
2. Disk types. You don't want to mix FC and SATA in the same aggr. You can, however, mix SAS and FC.
3. Political/Policy. Not all problems are technical. I've seen some environments where it's really important for certain data to live on their own disks (group A bought them, data security rules, etc.).
I'm sure there are other, but 90% of good reason I've seen fall into those 3 categories.
Hope this helps.
2010-03-06 12:35 PM
Another reason for more than one aggregate: reliability. For example, Exchange 2007 requires databases and logs sit on separate sets of disks. I agree with Adam that it is better to have a few large aggregates than many small aggregates.