on 06-22-2016 4:03 PM
Hello
In light of some problems we’ve been having, I was hoping someone could give me some information on SAP running on servers with disk redundancy in place.
We have a HP ProLiant DL380 Gen9 server, which has 64GB or RAM and dual processors. It runs on Windows Server 2012 R2 and SQL Server 2012. The hard disks are all set up to use RAID-5 redundancy, and it has SAP Business One (SQL version) installed.
We’ve noticed that the performance has been extremely slow from day one, sometimes taking around 40 seconds plus to open a document (e.g. sales quotation). With this in mind we decided to dig a little deeper into the problem, and after searching on the web, the consensus of opinion seemed to advise on not using RAID-5 for running SAP installations, but using RAID-1 or RAID-10 instead.
Does anyone have any guidance on this, whether SAP should or shouldn’t be installed on servers with RAID-5 in place, or, if there is a problem with it, are there any recommended settings which should be observed on RAID controllers in general (cache size, etc.)?
Any help on this gratefully received.
Many thanks.
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Thanks for all the replies.
I'm using Server 2012 R2. I have 3 x 300GB SAS drives (giving 600GB) for drive C, and 4 x 1TB SAS drives (giving 3TB) for drive D.
If I bought the extra drives, do you think there would really be any noticeable difference in speed between RAID-5 and RAID-10?
Thanks again.
Regards
Syner
Hello Syner,
usually, the Windows OS + pagefile fits on one disk well, which means 2 x 300 GB SAS building a RAID 1 is a common configuration. We still have many DL 380 (older generations) with 2 x 72 or 2 x 144 GB disks for the C: drive).
Then you have 6 disks left (assuming, you use max. no. of disks in your DL 380). You can build a nice RAID 10 which is much faster for write operations, but will it be enough speed for your application and your workload?
Nobody can predict that. Sorry.
You only can try. If you then afterwards see high disk queue lengths in Windows Resource Monitor then it wasn't worth all the work and time.
In that case you have to think about external storage solutions (SAS drive extensions, iSCSI or Fibre Channel based ...).
Best regards,
Kalle
Hello Syner,
there is no recommendation how you configure your server/storage solution. You have chosen to use internal disks of your brand new HP DL 380 Generation 9. How is your disk layout?
I guess:
2 SAS disks (RAID 1) for the Windows OS (C: partition)?
6 SAS disks (RAID 5) for the database & application?
RAID 5 is nice if you need as much space as you get get from a limited number of disks. Read performance is "not bad". But write performance is ... "limited" 🙂
RAID 1 (RAID 10 with many disks) needs more disks.
More disks, better performance. An old rule.
The RAID-Controller cache size is usually limited because you need a battery to keep it in case of power failure. New generations of RAID-Controllers doen't need the battery anymore, they use RAM chips from SSDs to store the cache.
You wrote that you use "Business One" with SQL-Server? Therefore I think you're using Windows OS? Which version? Did you already analyzed with Perfmon (or Windows Resource Monitor) which disk is the bottleneck? Which application does most reads / writes?
Best regards,
Kalle
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