May 3, 2018 at 3:30 pm
We are just starting to move to Azure VM's. We are thinking of creating an HADR (High Availability Disaster Recovery) set up. On prem we have been always used to having at least 3 to 4 VM drives for our databases. Data, Log, TembDB and Backup. This does give us an idea of what is growing how much even if with the new VM set up's you may not need to have data and log on different drives.
Going Azure VM route for our first database which is fairly small, at least initially. Was thinking of having Azure VM's have three drives for data, log and Backup. The build engineer thought having three drives may mean that we will get less I/o.
My question is, for Azure VM set up's is it ok/better to go with a single big drive and just put all the mdf, ldf, backup files on the same drive. What are the advantages/disadvantages in having such a set up.
Also, is having a single drive good or better for small databases?
Thanks,
Vips.
May 3, 2018 at 4:58 pm
Bharatvip - Thursday, May 3, 2018 3:30 PM...The build engineer thought having three drives may mean that we will get less I/o....
That is not true.
May 4, 2018 at 10:09 am
Single drives are always worse, since you lose everything with a failure. However, in Azure, you should have multiple copies from the infrastructure. You won't get less I/O from multiple drives. If that's documented, I'd ask the engineer where.
Follow me on Twitter: http://www.twitter.com/way0utwest
Forum Etiquette: How to post data/code on a forum to get the best help
My Blog: www.voiceofthedba.com
May 4, 2018 at 10:30 am
Thanks for you replies. I was trying to find what Microsoft recommends as far as the number of drives one should have for Azure VM's for sql server. Looked at some documentation, It is not very clear but seems like it is good to have one drive with all data, logs and backup files If you are using a disk striping technique, such as Storage Spaces. If you don't use disk striping then use multiple drives.
I guess there are are two things one is looking at while making a choice on the number of disks to go with. One is the i/o and looks like the i/o would be determined more by the type of storage in Azure that one decides to go with. Premium storage would provide higher i/o than standard. The other thing that Steve mentioned about 'losing everything to a failure' if we have all files on one disk. Would striping provide the same security that having three separate drives provides?
What would be nice to also know is if there is any downside in Azure VMs to having three separate drives instead of one. Do we lose anything?
Viewing 4 posts - 1 through 3 (of 3 total)
You must be logged in to reply to this topic. Login to reply