?
Solved

virtual drives on SAN

Posted on 2014-07-20
1
Medium Priority
?
330 Views
Last Modified: 2014-07-30
I am reviewing some redundancy based checks for a database application (MSSQL) but I wanted to gather your view as to whether these best practices are more geared towards physical servers and opposed virtual servers running on a SAN.

The best practice suggests separating database and log files and backups onto different drives, indicating if one drive dies then the other should be ok and it may not be a disaster.

But for drives on a VM hosted on a SAN - can individual drives on the VM still fail as they could in old physical drives. And by fail I mean can they fail in isolation, or would it be more likely the whole VM would fail as all the "virtual" drives on the VM are on the same hardware (SAN). If virtual drives can still die/fail in isolation even though they arent unique hardware as they would have been on an old physical server, can you give some pointers on how/common reasons they would fail/crash/whatever?
0
Comment
Question by:pma111
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
1 Comment
 
LVL 123

Accepted Solution

by:
Andrew Hancock (VMware vExpert / EE MVE^2) earned 2000 total points
ID: 40207777
There was a time that the statement you have made was applicable to Physical Servers and Direct Attached Storage. Because you had limited numbers of disks, and DBAs created Logs on RAID 1 Mirror (2 disks), DB on RAID 1 MIrror (2 disks).

It was done for performance, and disaster recover, because if logs were on separate disk to db, then you could recover transactions, and roll back etc

also logs could fill up the disk, so seperate disk LUNs were created.

However, rollout the SAN, and modern SANs, have many disks and shelves, which are all RAID-RP, RAID 6

and the disk presented for SQL, is either a datastore/VMDK or VHD, which is cut from the SAN on multiple spindles....

BUT, DBAs still like to create seperate disks for DB and Logs. (performance is likely to be the same as a single disk!)

Generally, I think if your SAN failed, ALL disks/LUNs and datastores would be unavailable...

However, there are many different SANs, and it's possible a LUN could fail, and you could be using two different LUNs for your SQL server.

So the example you give is still possible.
0

Featured Post

On Demand Webinar: Networking for the Cloud Era

Did you know SD-WANs can improve network connectivity? Check out this webinar to learn how an SD-WAN simplified, one-click tool can help you migrate and manage data in the cloud.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

The question appears often enough, how do I transfer my data from my old server to the new server while preserving file shares, share permissions, and NTFS permisions.  Here are my tips for handling such a transfer.
The business world is becoming increasingly integrated with tech. It’s not just for a select few anymore — but what about if you have a small business? It may be easier than you think to integrate technology into your small business, and it’s likely…
Viewers will learn how to use the INSERT statement to insert data into their tables. It will also introduce the NULL statement, to show them what happens when no value is giving for any given column.
This Micro Tutorial walks you through using a remote console to access a server and install ESXi 5.1. This example is showing remote access and installation using a Dell server. The hypervisor is the very first component of your virtual infrastructu…

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question