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SMART is not the whole story

Western Digital Drives - The Preferred Drives of FreeNAS and TrueNAS CORE
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Robert Trevellyan

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Just a reminder that a drive can be bad without anything showing up in SMART attributes or tests. This 500GB laptop drive passes short and extended SMART tests, and all SMART attributes look good, with not a single pending or reallocated sector. However, I noticed badblocks was taking a long time, to the point where the 1TB drive next to it in the dock was done many hours before this one. Running a quick benchmark reveals the issue, with catastrophically low write performance at intervals all across the drive, even though read performance seems OK.

Screenshot from 2016-06-17 18:27:03.png

No wonder my client was unhappy with the performance of his laptop.
 

Ericloewe

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That's odd behavior.... I can't really think of anything that would cause such a thing only for writes...
 

jgreco

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That's odd behavior.... I can't really think of anything that would cause such a thing only for writes...

Really? I see this on drives sometimes. We just RMA the drive. It's typically just a marginal drive that hasn't actually managed to get into a bad enough state that it actually fails the write, but is instead spending extra time in the write process and sorta-managing to succeed in the end.

This is much more common with laptop drives which are designed to succeed at their task in the challenging environment of sitting on someone's bouncy lap in the low pressure environment of a plane in flight, etc.
 

Mirfster

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Robert Trevellyan

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I decided to benchmark the used SATA drives I have on the shelf.

I thought I had:
2x 1TB
3x 640GB
7x 500GB
2x 360GB
4x 320GB
3x 250GB
4x 160GB
1x 120GB
2x 80GB
because they had all passed SMART short, extended and badblocks tests.

Turns out I actually have:
1x 1TB
2x 640GB
6x 500GB
2x 360GB
3x 320GB
3x 250GB
3x 160GB
1x 120GB
2x 80GB
because all the others have abysmal write performance over a significant portion of the disk surface. The duds are 2x WD Black and 3x WD Blue (5 out of 28).
:(

I'll be adding benchmarking to my burn-in process for new drives.

In other news, yes, I still have a couple of 80GB drives.
 

jgreco

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There's a reason that the array test script we use here (search for it on the forums) measures drive speeds and reports anomalies. In the old days, this was actually *the* best way to measure drive health.
 

Jailer

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jgreco

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I've still got 2 Maxtor 40GB drives.

Surely you misspoke. Surely you meant 40MB. *whips out the ol' WD93044A*. That's about as far as I go back for IDE, but I've got some great RLL, MFM, SCSI, and ESDI stuff around.
 

Jailer

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I'm pretty new to the game having not touched a single computer until 2000. Those drives are about as old of hardware I have around.
 

Spearfoot

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maglin

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My first computer was a 386-DX2. Man it was fast. With 4MB of RAM and a 40MB HDD. I still remember when Windows 3.1 quickly followed by Win95 came out. Man all those floppy disks. I wanted more RAM for playing Spellbound I think it was and 4MB of RAM was $410. Needless to say I made do with what I had.
 

jgreco

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My first computer was a 386-DX2. Man it was fast. With 4MB of RAM and a 40MB HDD. I still remember when Windows 3.1 quickly followed by Win95 came out. Man all those floppy disks. I wanted more RAM for playing Spellbound I think it was and 4MB of RAM was $410. Needless to say I made do with what I had.

I've still got a 386sx-16 that used to be able to run FreeBSD before FreeBSD got all bloated.
 

Mirfster

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Dude, check your glasses, that's a 20 *GB* drive.
Ah, glossed right over that... Okay, now <20 *MB* is the goal....

/Edit: Just realized I meant "<20 *MB*" instead of ">20 *MB*"
 
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jgreco

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Ah, glossed right over that... Okay, now >20 *MB* is the goal....

You're forgiven ... that Microsoft article was a great catch and I've updated the "multiple interfaces" article accordingly, by the way.
 

Spearfoot

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You guys are really making me feel old... my first computer was an 80286 AT clone with 1MB of RAM.
 

Robert Trevellyan

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my first computer
<sigh>
OK, I'll play. I had a BBC Micro Model B with 32KB RAM, a 2MHz 6502, and a cassette tape interface for "non-volatile" storage. The 320KB 5.25" floppy drive was a major upgrade.

If you want to know where the ARM came from, go read about this machine on Wikipedia.
 
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