Netbackup Disk Performance & Caching on Windows
I’m trying to tune a disk performance issue on a NetBackup 7.1.04 system.
Media Server Deduplication (MSDP) is used.
Media Server Hardware: HP DL360 G7 2 x Quad-core CPU’s, 32TB RAM, Windows 2008 R2, SmartArray P812 (w/1024MB cache) controller for MSDP disk, QLogic Dual-port 8gbps fibre-channel HBA
MSDP Disk: 2 x 12 x 2TB Midline SAS drives in 2 x HP D2600 enclosures. Connected via SAS cables in HP recommended configuration (fully redundant, multiple pathways). RAID6
Tape: HP MSL4048 library with 2 x Ultrium 3000 LTO5 drives connected via 8gbps Fibre channel to f/c fabric.
The problem: Tape write performance is only reaching 25MB/s due to what appears to be a DISK READ bottleneck on the MSDP disk pool
I’ve collected perfmon stats over the weekend when all the tape backups are running and observed that:
MSDP DISK READ Queue is constantly above 3 (whereas DISK WRITE Queue is only 0.1)
MSDP % DISK READ time is 300 – 450% (whereas %DISK WRITE Time is less than 15%)
MSDP AVG DISK BYTES/READ = 90KB
MSDP AVG DISK BYTES/WRITE = 150 – 210KB
MEMORY AVAILABLE MEGABYTES = 9000 – 12000MB (9 – 12GB!)
Those stats suggest to me that the READ’s are the bottleneck, and there is a significant amount of RAM sitting unused.
So my questions are:
- Is there any NetBackup tuning recommendations to improve READ caching (either in Netbackup or in the Windows OS) to make better use of all that free RAM?
- SmartArray controller has an adjustable Read:Write ratio, currently set to default 25% Read : 75% Write. Would you recommend changing that to favour Reads eg. 50:50?
- What is the recommended RAID stripe size for a 32TB MSDP disk array (HP’s default stripe size is 256KB, but it can also be set to 16K, 32K, 64K, 128K)?
We have already tried increasing NBU Buffers:
NUMBER_DATA_BUFFERS = 512
SIZE_DATA_BUFFERS = 524288
NUMBER_DATA_BUFFERS_DISK = 512
SIZE_DATA_BUFFERS_DISK = 1048576
And we’ve reviewed the NBU 7.1 Tuning guide for Windows and these articles:
Any hints or tips would be appreciated.