SAS Expanders are a newer storage technology that lets you maximize the storage capability of your SAS controller card. Many SAS controllers support up to 128 or more hard drives. This can only be done with a SAS expander solution. Since many people are still unfamiliar with SAS Expansion, this site compares it to several storage technologies.
Why SAS Expanders?
- Expanders are the only way to achieve storage capacity beyond 8, 12, 16 or 24 drives with a single controller card. Most external port cards have two ports and can support only 8 drives without an expander.
- Expander enclosures give flexibility of adding more expander enclosures later by way of daisy chaining (see left pic).
- Single external multilane cable per enclosure.
- No adapters to convert internal ports to external.
- Can use the latest and greatest controllers and hard drives.
- Can use low cost SATA drives as well as SAS drives and SSDs.
However, the key difference... what happens after the 12th, 16th or 24th drive?
These charts show the pros & cons of expanders vs. other options:
more: Frequently Asked Questions (FAQ)
more: Serial Attached SCSI (wikipedia.org)
How Much Do They Cost?
Q: Are SAS Expanders more expensive than other storage technologies?
A: The enclosures are a bit more expensive; you save on everything else.
In many cases, the costs are comparable with other storage technologies,
while giving you more in terms of simplicity, flexibility and futureproofing.
SAS Expander Enclosures are now available in Tower, 2U, 3U and 4U.