Backup
Performance – The 8GB/Min Goal
Our future storage space
requirements were estimated to be 4 TB. Our requirement is to complete the
backups within an 8 hour window. To meet this objective required a backup
solution that could provide an 8 GB/Min solution. We researched several
technologies to obtain the required level of performance. After months of
research we decided to base our solution around an article written by HP,
“Getting the most performance from your HP StorageWorks Ultrium 960 tape
drive[1]”.
This white paper discussed several technologies and methodologies to obtain the
performance levels desired. The article also provide information for combining
our backup solution of choice, Veritas NetBackup[2] and
used hardware that had excellent reviews[3].
During this process we decided to use a DAS and NAS storage solution. We
decided to avoid SAN storage and disk to disk storage because of the overhead,
complexity, and cost associated with these technologies. In addition, we
decided to implement a single vendor solution to enhance support. Once our
design was in place with worked with multiple resellers and the manufacture, HP
directly to insure the equipment ordered with meet or exceed the performance
levels outlined in the HP performance article above. Once the equipment was in
place we were unable to obtain the results documented. The article highlights
some of our findings along the way. I think our findings will raise an eyebrow
or two and you will find it a worthy read. After our ordeal we did identify a
technique to obtain the performance desired. After reading this article if you
have experienced the same challenges or are equally disappointed with
HP’s position we would like to hear from you. Below is our tale.
Objective: Setup a simple, scalable, high performance single
vendor DAS backup solution.
Hardware:
DL580 G3
Dual
Processor
4
GB RAM (2 GB per processor)
4
15K RPM drives
LSI Ultra 320 SCSI
Controller for Tape Storage Unit
Max
SCSI cache memory and battery to enable write back cache
MSA500 G2
Model with dual Ultra 320 SCSI channel
14 15K RPM, 72 GB Drives for performance
MSA30
14 15K RPM, 72 GB Drives for performance
Model with dual Ultra 320 SCSI channels
MSL6030
17 TB Backup storage capacity
Dual LTO 3 drives for performance and required backup operations
Software Tools Utilized:
Intel Iometer
HP PAT (Performance Analysis Tool)
HP Read Data
Windows Explorer file copy
HP Library & Tape tool Prebackup
test
Tests:
Over several months working with HP we tried a
myriad of configurations and tests.
These tests included but are not limited to the following.
Various Windows 2003 Server Service Packs &
Hotfixes
BIOS updates for system, SCSI, Drives, Tape Lib,
Tape Drive etc.
Driver updates and versions for system, array
controller, and tape
Differing drivers to include both SCSI Mini-Port
and Non-Mini-Port drivers
Changing strip size on drive arrays
Changing RAID level from 0, 1, 5, and 10.
Changing Read/Write cache Levels
Changing SCSI driver parameters
Changing software buffer, memory, and block size
parameters
Using dual data channels to MSA500
These tests were repeated using an MSA30.
Testing Results:
·
Stripe size, Number of drives and
RAID level made no significance impact on the performance.
·
MSA 500 G2 does not use two independent SCSI
channels. The second SCSI interface is only for failover and redundancy. With
the same configuration MSA 30 outperforms MSA 500 G2 using single SCSI channel.
·
“Iometer” provides unusually high
through put results. We learned that this tool bypasses the Windows system
drivers. Therefore this tool is not an accurate measure of the performance.
·
“HP PAT” also bypasses Windows system
drivers and is not recommended for benchmarking.
·
The test data created by “HP Create Data”
utility is euphoria data and is not realistic. The data sizes created are
perfect and no performance loss is realized with SCSI data packets that range
in sizes. Expect your results to be approximately 50% or worse then the
performance numbers obtained using this data. “HP Read data”,
“HP Prebackup test”, “Windows Explorer” file copy and
“VERITAS Netbackup” Null test provided comparable performance
results and were consistent with ‘real world’ findings.
·
Performance was never any better than it would have
been with a single drive. It runs as fast as the single drive.
·
Performance was related to number of logical units
(LUN). Results obtained were 3 to 4 times better when LUNs were increased.
·
HP SCSI drivers for Microsoft Windows have a 64K
block size
