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I'm a software engineer, not a system admin, so if this question seems a little green you know why! ;-)

As a personal project I've been working on a home NAS system using FreeNAS. One of the features of FreeNAS is the ability setup a SMART check to run ever X number of seconds. By default this is set to run every 1800 seconds (30 minutes). This seemed high to me though, is this really a reasonable value? I would think checking once every 6 hours or something would be reasonable enough...

So my question is: How frequently should a SMART check be run on a drive?

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up vote 7 down vote accepted

I'm not sure what you mean.

  • You can ask the disk to run a (SMART) self-test. This usually takes some time, and is somewhat stressful for the disk. I'd not recommend to run it more than once in a long while.

  • On the other hand, you can check the SMART status from the disk. In other words, this means "read the SMART meters from the disk". This operation is simple and fast, and can be run how many times you want.

Supposing you are asking for checking the SMART status, then every 60, 30, 15, 10 or 5 minutes, or whatever is good enough. It doesn't matter. In this case, it is more important WHAT will be done with such reading. Will it be logged? Will it be checked for failure and e-mailed when a failure is detected? After all, it makes little sense to read the status every minute if you, the admin, will only look at this once in a month.

If you need help, maybe the smartmontools project might be useful. (at least you can check its source code to see how often smartd reads the status)

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I'm using the 0.7rc1 version of FreeNAS, which has redone their SMART support and the documentation has not caught up yet... But I would guess that they mean "read the SMART meters from the disk" and not a self-test. The question still remains though on how long you should log this status info... – Petriborg Sep 14 '09 at 12:36
I'd say you should keep SMART logs as long as you keep all other logs. In my humble opinion, I'd keep for at least one month. – Denilson Sá Sep 14 '09 at 19:49
Freenas uses smartctrl for their tests,, and takes the language around their tests from that tool. I am not sure if the "self-tests" are the full on tests that you are describing above, or just status checks. – James McMahon Jul 23 '12 at 16:10

I run a short SMART test every morning that takes about 5 minutes on all of my 1.5 to 2TB drives. Then once a week I run a long SMART test that takes about 7 hours. I'm under the impression that these tests do not stress the drives in any way and the only confirmation I have of this is that their temperature remains at baseline (about 37C) during the long tests. The outputs are parsed, filtered and emailed back to me in a daily report.

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SMART tests do not impose any "stress" on the disk and will not shorten their life. I am using the same schedule (daily short tests, weekly long tests) on all the systems I manage (including both mechanical disks and SSDs), dozens of disks have passed through this in the last years. – Luke404 Jan 15 at 18:52

Quote from the official FAQ

If your ATA drive supports self-tests, you should run them on a regular basis, for example one per week:

     smartctl -t long /dev/hd?

After the test has completed, you should examine the results with:

     smartctl -l selftest /dev/hd?
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SMART helps to detect indicates that suggest the disk is likely to fail. It's possible for a disk to fail a SMART test and still seem to work fine for weeks or even months. Every 30 minutes seems fine to me...

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So you feel logging it more often would better or do you just not think it matters that much? – Petriborg Sep 14 '09 at 12:40

Since the Smart Daemon only checks values stored in the cpu of the hard disk, you can run it as frequest as you wish. the idea is to recognize problem as quickly as they happen, because they really are a sign of imminent disk problems.

I have had a hard disk fail me within days of getting smart notifications.

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