VMware SAN or Local Storage
Experts,
Currently, I have VMware ESXi 5.1 that runs on two Dell Power Edge 2970 Servers in my corporate office and one Dell Power Edge 2970 in a remote location. These servers run off of hard disks that are inside each server. I believe these disks are SAS 7.2. There are 6 disks in each server. 0 and 1 are a mirrored configuration and I run my backups on the mirror. Disks 2,3,4, and 5 are in a RAID 5 configuration and this is the main datastore in VMware where the machines (Microsoft 2003 server, MySQL, XP....etc) are stored and run from.
I am looking into the possibility of purchasing a SAN, so that I could have some centralized storage, but am not familiar with the technology and am researching all options available. I have attached a report of some metrics that were gathered regarding the performance of my current servers. It would be helpful if I fully understood what this collected data really means. I believe it would help make my decision easier. For instance, I know IOPS are important, but 755.4 at 95%, 1071.3 at 99% and 1315.0 at peak means nothing to me. Is there anyone out there that can break down what this report is telling me? Also, I would welcome advice on what people are using in the real world as far as storage and what hardware is giving good performance in a production environment.
Your advice and assistance in this matter is greatly appreciated!
machine-metrics.pdf
Currently, I have VMware ESXi 5.1 that runs on two Dell Power Edge 2970 Servers in my corporate office and one Dell Power Edge 2970 in a remote location. These servers run off of hard disks that are inside each server. I believe these disks are SAS 7.2. There are 6 disks in each server. 0 and 1 are a mirrored configuration and I run my backups on the mirror. Disks 2,3,4, and 5 are in a RAID 5 configuration and this is the main datastore in VMware where the machines (Microsoft 2003 server, MySQL, XP....etc) are stored and run from.
I am looking into the possibility of purchasing a SAN, so that I could have some centralized storage, but am not familiar with the technology and am researching all options available. I have attached a report of some metrics that were gathered regarding the performance of my current servers. It would be helpful if I fully understood what this collected data really means. I believe it would help make my decision easier. For instance, I know IOPS are important, but 755.4 at 95%, 1071.3 at 99% and 1315.0 at peak means nothing to me. Is there anyone out there that can break down what this report is telling me? Also, I would welcome advice on what people are using in the real world as far as storage and what hardware is giving good performance in a production environment.
Your advice and assistance in this matter is greatly appreciated!
machine-metrics.pdf
ASKER
I currently have Essentials, not Essentials Plus. I am considering purchasing the Standard version. About a month ago I lost the Raid 5 in both servers and had to rebuild. I had my backups on the mirrored partition so I did not actually lose my data, it was just painful rebuilding. Looking to try to mitigate down time if my RAIDs fail again.
A SAN or even better a NAS would be your choice. For most people SAN's are an investment as you will have to buy then "of-course" and possibly upgrade your existing hosts with HBA cards [not cheap] and also an FC switch. A NAS on the other hand will make use of your existing Ethernet network using iSCSI, and if you have gigabit switches already ... :-)
I'd use a NAS in your situation, configure jumbo frames support on the switchport and vmkernel port and increase the MTU size to 9000.
I'd use a NAS in your situation, configure jumbo frames support on the switchport and vmkernel port and increase the MTU size to 9000.
ASKER
Do you have any NAS recommendations? I have tried hooking up a Netgear NAS and the performance was horrible. It was really slow.
Remember SANs also FAIL its only RAID!
More disks with more chance to fail....
Get a good backup or two SANs
More disks with more chance to fail....
Get a good backup or two SANs
And with more disks takes longer to rebuild and restore
And is one very large single point of failure
And is one very large single point of failure
ASKER
I have no experience with SANs so I just want to make sure my thought process on the use of a SAN is correct. I would have a SAN with multiple ethernet connections and then the two power edge servers would plug in to the one san. The SAN would then be added as a Datastore in ESXi and then I would create my virtual machines on that Datastore and run the servers from the SAN. If this is the case, is the performance of the server good?
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Also use IOMeter to benchmark your servers disk IOPS, it gives a better output.
http://www.iometer.org/
http://www.iometer.org/
ASKER
Dipopo you have provided great information that I can use. Just one final question to you, can you tell me in terms I can understand what the document I have attached to this question is telling me? It is an output from a Dpack that was run. The person that was going over it with me was very rushed and I didn't really quite understand what the heck he was talking about. Does it make any sense to you? If not that's okay....was just trying to understand!
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I just want to make few things simple.
Each sata disk(7200rpm) does 120 to 130 IOPS on average.
Each Fiber channel disk(15krpm) does 180 IOPS on average.
So if you have a server with 4 disks in a raid , it can do 500 IO/sec. Beyound that is not an opted performance.
Again if get what you pay for, other imp issue you have to consider while you invest in SAN storage is cache, which is a value measure for the performance. There are storage boxes from 512 mb cache to 2 TB cache.
Just my 2 cents to consider.
Each sata disk(7200rpm) does 120 to 130 IOPS on average.
Each Fiber channel disk(15krpm) does 180 IOPS on average.
So if you have a server with 4 disks in a raid , it can do 500 IO/sec. Beyound that is not an opted performance.
Again if get what you pay for, other imp issue you have to consider while you invest in SAN storage is cache, which is a value measure for the performance. There are storage boxes from 512 mb cache to 2 TB cache.
Just my 2 cents to consider.
The IOPs percentile is based on workload, see below:
It means 95 % of the time the IOPs usage is below the figure provided.
95% of the time IOPs below 755.4
98% of the time IOPs below 1071.3
Peak usage is below 1315.0
Also the figures for your CPU and Memory look OK to me.
Another thing is this, I prefer RDM disks with such applications like SQL, try not to use virtual disks for SQL as the scsi commands/activity go via the vmkernel and creates overhead. I tend to use Raw device mappings direct from my SAN/NAS Luns to the VM for these.
It means 95 % of the time the IOPs usage is below the figure provided.
95% of the time IOPs below 755.4
98% of the time IOPs below 1071.3
Peak usage is below 1315.0
Also the figures for your CPU and Memory look OK to me.
Another thing is this, I prefer RDM disks with such applications like SQL, try not to use virtual disks for SQL as the scsi commands/activity go via the vmkernel and creates overhead. I tend to use Raw device mappings direct from my SAN/NAS Luns to the VM for these.
ASKER
Thank you for the response. You have provided very valuable information!
Do you also have licensed for VMware vSphere which can take advantage of shared storage features?
e.g. VMware HA, VMware DRS and vMotion?