wrote:

Observe that I did not give you advice on what the best solution for
you is. That depends on too many factors; most importantly, the depth
of your pocketbook versus your tolerance for pain and suffering, which
is to say whether availability or low cost is more important to you.

Thanks - I have some new insights now. Some other thing that occured to
me: look at manufacturer data.

Seagate publish an IDC document: MTBF of desktop ATA drive is half that
of enterprise FCAL drive, and they give MaXline and their own NL35
series as filling the gap.

Cheetah 10K:
10E-15 unrecoverable read errors per bit read
0.62% annual failure rate

NL35:
10E-14 unrecoverable read errors per bit read
MTBF specified for 'nearline workload': 1M hours, which is 0.9% AFR.

Barracuda:
10E-14 unrecoverable read errors per bit read
no MTBF or even seek time specified. Yuk, they still call it a data sheet.

Now, my workload will read about 2 megabytes/sec per drive - for FCAL
I'd be aiming at 3 MB/s. SATA will give me a bad block once every 30
years on a single drive when I just use the published rate.

This is about the rate that I see. Thus, SATA without RAID to catch more
errors is not usable - and neither is FCAL.

But it is drives breaking that worries me.


Thomas