Choosing RAID Levels for LUNs
Use RAID 1 for metadata LUNs and RAID 5 for data LUNs.
Use RAID 1 for Metadata LUNs
RAID 1 (mirroring) can give slightly better performance than the default RAID 5
scheme for the small, two-drive metadata LUNs that Xsan uses to store volume
information. A single drive is almost always adequate for storing the primary volume
metadata. (10 GB of metadata space is enough for approximately 10 million files.)
The second, mirror drive protects you against metadata loss.
Use RAID 5 for Data LUNs
Most RAID systems are optimized for excellent performance and data redundancy
using a RAID 5 scheme. (RAID 5 stripes data across the available drives and also
distributes parity data across the drives.) Some RAID systems ship preconfigured
as RAID 5 LUNs. RAID 0 (striping with no parity) might give slightly better write
performance, but it provides no data recovery protection, so RAID 5 is always a better
choice for LUNs used to store user data.
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Chapter 2
Planning a Storage Area Network
Chapter 2
Planning a Storage Area Network
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