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SAS vs "Near line" SAS

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What's the difference between SAS drives and Near-line SAS drives? I've found a little information saying that the nearlines use SATA drives with a SAS interface board. Is that correct? What is the benefit/drawback of using nearline vs pure SAS? I've noticed that SAS seems to come in smaller capacities but with higher rotational speeds, while the nearline SAS is the opposite. Also the nearlines are cheaper.

I'm looking at them for an oracle database server. The extra space of a nearline would be nice, but so would the speed of the real SAS.

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Nearline is to provide "cheap" huge space for backup and not so frequently accessed files. Low to moderate IOPS and typically 10k rpm drives. But they are real SAS drives.

For a production Oracle DB, it depends on your applications profile (e.g. data warehousing, online transaction system, count of users) and size. Not every application needs

15k Savvios!

But if you have a DB with lots and heavy write transactions, you will want as much IOPS you can get e.g. for the REDO logs and/or UNDO-Tablespaces.

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The database is used in a mixed environment of online transactions and reporting, and it's the reporting that's what really hits the server. I'm in the process of switching us over from a software(!) RAID5(!) running on very old (like 7 years old(!)) sun boxes, to a new Intel server running hardware RAID10. I'm not sure if the speed difference between 15K SAS and 7K Nearlines will even be noticed by the users since it's going to blow their heads off anyway...

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I'm looking at them for an oracle database server. The extra space of a nearline would be nice, but so would the speed of the real SAS.

On OLTP DB platforms, "Intel's entering SSD market" made me changed my recos to SATAs drives:

-Non production platforms : I always go SATA on those but I can build

-Large volumes with small concurrent users : SATA raid 6 (DATA INDEX) and SATA raid 1 (LOG)

-High concurrent users : Some (Intel, MTron Pro or Samsung) SSD (in raid 0 because of the SMART anticipation capability) for high concurrent tables + SATA raid as above

-Of course, I always have 64 bits DB platforms (some Linux 2.6 now) with 16, 32 or 64GB RAM + Full Backup

-When the app is critical, I deploy a secondary DB (RAC or LOGs adjusted copy)

==> So I have:

-1 GB for 0.26 EUR (raid 6)

-1 super fast GB for 10 to 15 EUR (raid 0)

-Twice this cost for critical apps

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Near line sas are bascially SATA drive that can fit SAS connections.

Same speed really as SATA.

But good if you need 1TB drives in a SAS server, say for backups or something like that.

Not good for first or primary storage in a SAS based srever.

You might as well go with SATA if you want them as main storage.

SAS servers are good for speed and performance.

Collected from: Ryan Berglund from The Planet Live Chat

Moin Uddin

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