How to achieve over 2 TB/hr network backup with Integrity entry-class servers running HP-UX 11i v3

Overall testing found that the most optimal tuning combination for this particular backup server

configuration was 32 buffers and 256KB I/O blocks. Figure 2 shows that two HP LTO-4 tape devices

given the data mix used for this test effort can back up 450 MB/s total, or an average of 225 MB/s

per LTO-4 tape device.

Figure 2: Backup utility tuning settings for number of I/O buffers and size of blocks

The 256KB I/O block size for the backup utility tunable is ideal for systems running the Online JFS

product. With Online JFS and no additional file-system tuning, this larger I/O block size implicitly

enables the Online JFS Direct I/O feature for file reads. The feature can also be tuned using the

vxtunefs command to set the JFS (VxFS) file-system tunable discovered_direct_iosz, which is

available with VxFS v4.1 and newer versions. With Online JFS, Direct I/O is enabled implicitly if

the read or write size is greater than or equal to the value set for the discovered_direct_iosz

tunable. The default value for discovered_direct_iosz is 256 KB.

With Direct I/O enabled, read data goes directly to the user buffer and bypasses the file buffer cache

of the operating system. This avoids a memory copy of file data between buffers and reduces CPU

utilization, thereby increasing overall backup performance.

For information about additional file system tuning capabilities available on client systems, see the

“JFS Tuning and Performance” white paper available at:

http://www.hp.com/go/hpux-core-docs

(click on the HP-UX 11i v3 product link)

The following subsections describe stress test results for the 1GbE port and the LTO-4 throughput

limits. To demonstrate how backup utility tuning can affect overall throughput, the tests use the backup

utility tuning combinations of 8 buffers/64KB blocks and 32 buffers/256KB blocks.

Note

Because this network backup server characterization analyzes data storage I/O throughput

instead of network bandwidth, data rates are measured and reported in bytes (B) rather than bits

(b).

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6 Clients

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8 Clients

Data Throughput (MB/s)

Two Data Streams per Client

16 buff/128KB blk

16 buff/256KB blk

32 buff/128KB blk

32 buff/256KB blk