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For a power workstation, which is better (I'm thinking of doing a RAID 5 configuration). 15K RPM serial-attached SCSI drives, or SATA solid state drives?

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Update and practical guidance that builds on and without repeating their points.

Modern context: for a performance workstation the balance has shifted — low-latency, high‑random‑IOPS SSDs (especially NVMe) outperform 15K‑RPM SAS drives for interactive workloads (VMs, editing, compiles, databases), while spinning disks still win on raw $/GB for bulk storage. Choose the media that matches the workload: SSDs for responsiveness and random I/O, HDDs for cheap sequential capacity. (techtarget.com)

Durability and redundancy: large drives and large RAID‑5 groups increase rebuild time and expose you to unrecoverable read errors during a rebuild. For anything more than a small, low‑capacity array avoid RAID‑5; use RAID‑10 for write-heavy work or RAID‑6 / erasure coding where capacity efficiency with double parity is needed. RAID choice should be driven by rebuild window, array size, and how quickly you can replace failed drives. (en.wikipedia.org)

Controller and stack notes: firmware and controller behavior still matter. Hardware RAID/older HBAs historically did not pass TRIM/UNMAP through to SSDs, which affects long‑term performance; modern tri‑mode controllers or using an HBA in IT mode with software RAID avoids many of these pitfalls. Verify controller TRIM/UNMAP support and current firmware before deploying SSDs in RAID. (en.wikipedia.org)

How to pick drives and a short checklist: prefer enterprise SSDs for sustained write loads (look for TBW or DWPD ratings, power‑loss protection, end‑to‑end data protection and clear vendor telemetry). Leave spare/free space or use overprovisioning, monitor SMART/TBW, keep controller firmware current, and plan backups — RAID is availability, not a backup. For a power workstation: mirror the boot/scratch SSDs (RAID1), use RAID10 for critical fast storage, and reserve HDD/SAS arrays for bulk capacity if budget dictates. (studylib.net)

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Member Avatar for rch1231

Dani,

That would be a tough choice to make and would depend on what SSD drives are available. I have always heard that SSD drives did not have a great life expectancy if you do a lot of writes to the drives however every site I look at says they are much better now and have the potential to last longer that a standard drive. The problem is that the technology is so new that we don't really have any SSD drives that have been in use for 10 years to examine.
If your running a RAID 5 array your going to get the speed of striped data to and from the array controller by the controller. The company I work for supplies SSD drives and it seems to me that we are replacing a lot of them that have failed and in some cases more than one that failed in an array at a time and we are also doing a lot upgrades to the latest controller firmware due to issues being addressed.

Personally I would say unless you are really in need of much greater speed, go with the SAS array and give the SSD drives time to get out there and get the controller and life expectancy issues fixed.

Member Avatar for rubberman

For a system drive (read-mostly, write occasionally) then an SSD is a good choice (mirrored drives for reliability). For data storage (a lot of writing and over-writing, database, etc) then you want spinning media in a RAID-5 or RAID-10 configuration. The reason for this is that current generation SSD's have a limited number of cell writes before the cell becomes useless. Current SSD controller software mitigates this by trying not to write updates to the same cell, and if you are using well less than 50% of the drive, this is good and gives decent life to an SSD, but not all are created equal. For SSD's, get "industrial" strength devices (pricey). For hard-drive RAID's, get commodity (but good quality) devices. There is always the tradeoffs between price, performance, and longevity.

commented: Agreed. I typically use SSD for OS drives and magnetic storage for everything else. My last SSD has lasted 3 years like this and shows no signs of failure yet. However, the Vertex 2 I used for write-heavy operations and it died within 14 months +11
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