MaxDB 7.6 on NFS, NAS?

[former_member192710]

Folks;

being into storage consolidation, we so far deal with the idea of moving data and application off our servers to a NAS appliance. In order to choose a good technology on that:

• The technologies in question all do offer NFS support (we're running MaxDB atop Linux). Is running MaxDB 7.6 off an NFS mount a good idea in terms of stability and performance? Are there any pitfalls to be aware of here?

• Considering system options, our storage consultant explained that Solaris in some situations seems to do better in regards to NFS than Linux. Given that we're just talking about the database server where operating system doesn't matter that much and there's also a MaxDB build for Solaris out there, would there be any gain from moving our MaxDB installation to a Solaris (10, x86) machine? Any things we should take care of here?

• Overally, in order to have MaxDB run in a NAS environment, considering both performance/stability and overall costs of this solution, our consultant so far has offered using either an NFS based approach or attaching a storage box using iSCSI, both assuming storage is connected to the servers using a dedicated (GBE) LAN. What technology would be preferrable here?

Thanks in advance for any hints, best regards.

Kristian

[markus_doehr2 · Accepted solution]

> * Considering system options, our storage consultant explained that Solaris in some situations seems to do better in regards to NFS than Linux.

Can you (or your consultant) please elaborate what you mean with "better"?

> * Overally, in order to have MaxDB run in a NAS environment, considering both performance/stability and overall costs of this solution, our consultant so far has offered using either an NFS based approach or attaching a storage box using iSCSI, both assuming storage is connected to the servers using a dedicated (GBE) LAN. What technology would be preferrable here?

I personally would never put a database server on an NFS based storage. We tried that in the past with a NetApp and the speed was beyond horrible (even with dedicated switched LAN connections) compared to a fibrechannel based connection.

Technically it's not an issue, neither with Solaris nor Linux but latency issues may arise on the NFS client. Of course, the NFS protocol itself is improving and with NFSv4 you may be as fast as with direct connected storage but I haven't tested that and thus can't state on it.

MaxDB uses an 8 kb blocksize to read the data, the speed of the database is mainly defined by the single read speed of a block (apart from special configurations using e. g. prefetching). Using TCP/IP as communication protocol (for both NAS an NFS) adds an additional layer and thus may increase latency, however, the speed can be enough for you, that's something you need to find out yourself (testing, testing, testing).

If you're unsure I'd ask the vendors if they can give you a system for testing. It's the best way to find out, what configuration suits best for your environment. I can just comment on ours.

Markus

[former_member192710 · Accepted solution]

Hi Markus;

and first off, thanks for your thoughts on that...

>

> > * Considering system options, our storage consultant explained that Solaris in some situations seems to do better in regards to NFS than Linux.

>

> Can you (or your consultant) please elaborate what you mean with "better"?

I am not that familiar with NFS overally as so far we're not using it in any installment; I think the main reasoning was something like Solaris providing a bunch of additional NFS mount options to allow for some more extensive performance tuning on that level compared to Linux. As said, I am looking for second opinions on that as well.

> I personally would never put a database server on an NFS based storage. We tried that in the past with a NetApp and the speed was beyond horrible (even with dedicated switched LAN connections) compared to a fibrechannel based connection.

That also was my first thought about moving the database system off the server-attached storage, yet we are searching for a unified solution in this field and, other way, the database is the only application that eventually would require something faster than NFS or CIFS. Anway, thanks a bunch for your considered comments on this issue - as said, so far we're totally lacking any experiences in this field; our storage consultant apparently has been through a project of moving an Oracle database to a NetApp system with pretty good results involving iSCSI (not NFS); we indeed will have to do some test-runs and see how things overally do.

Thanks and bye,

Kristian

[markus_doehr2 · Accepted solution]

>our storage consultant apparently has been through a project of moving an Oracle database to a NetApp system with pretty good results involving iSCSI (not NFS); we indeed will have to do some test-runs and see how things overally do.

Oracle works much better using NFS due to its different method of reading data (reading multiple chunks with one I/O, using bigger blocks etc.). That concept is not transferable to MaxDB.

You may be satisfied with iSCSI for MaxDB, the difference between fibrechannel and iSCSI is not that big.

Markus

[Former Member · Accepted solution]

Hi,

comparing iSCSI vs FC we determined a huge difference in the performance of the MaxDB. The installation on basis of iSCSI was quit slowly. You should pay attention to the log devices. Whenever it is possible you should avoid log file on iSCSI devices. Put them on faster devices like SAS or even better FC devices. With a huge data cache you may get satisfying results for the data devices (because of the minimized device accesses) but not for the log devices.

I got the impression the iSCSI based SAP systems is three times slower than the FC based SAP system. But this is just an impression without any hard facts. For me it was enough to see that an iSCSI based SAP system becomes so slow.

Regards

André

[markus_doehr2 · Accepted solution]

comparing iSCSI vs FC we determined a huge difference in the performance of the MaxDB.

That´s interesting...

We didn´t see any real big differences during runtime but of course, the installation was slower and this was expected; that´s what I wanted to describe as "latency". I depends on the application used. If you do just "a bit Solutionmanager" it may be fast enough, for a highly loaded ERP system it may be too slow.

Markus

[former_member192710 · Accepted solution]

Markus, Andre;

first off, thanks a bunch for your thoughts on that. Looking at our environment (we're not using MaxDB along with other SAP applications), our database so far is rather limited in size (about 4GB so far), and having it moved off to the storage mainly would be a matter of convenience. So we have decided to go for iSCSI for the sake of affordability and, in case performance is not up to our needs, move the database instance itself back to server-attached storage systems and just keep backups on the filer which also would make things a bit easier than they are now.

Thanks for your input on that.

Best regards,

Kristian

[Former Member · Accepted solution]

Hi Kristian,

Do you mind sharing how this project turned out?

We are considering moving our SAP environment to Win/MaxDB on an iSCSI storage subsystem. I would like to know if you kept your MaxDB on the iSCSI storage system? How was the performance?

Thanks,

Roy Brasse