I recently ran into a situation where a RAID drive had to be replaced.  So I got another 40GB drive (yes - very old PC).  It was the same brand and model (WD400-BB) but with a slight different suffix to the drive model (WD400BB-75JHA0 vs. WD400-22xxxx).  Here's the fun part.  It was about 20MB smaller than the other drive.  Bottom line - the RAID won't accept it because it's smaller.

Why would that be (same model drive slightly smaller) and how would I have been able to see the exact size to avoid this.  I don't see it in the specs.  Hosed again.

It could be that the drives use different cluster sizes, or that the specs for one were made using 1,000 for 1K, and the other with 1024 for 1K. Meanwhile, getting a significantly larger drive compatible drive should get you going. We just retired a server after 10 years, that had 17GB drives in one array, and 70GB drives in another. When we had to replace a hot spare that had taken the place of a failed drive, on occasion we used a 30GB drive to replace a 17GB unit, and it 'just worked'. These were 14-drive arrays, and all the drives were from the original manufacturer, just different sizes.

Fred Wagner

  

Yeah, I know all about the "larger is fine, small doesn't work" for a RAID array drive replacement, but I just had no clue that the same brand/model drive would vary by even 1KB.

Could it be a significantly larger number of clusters in the 'Bad- do not use' table ?

Fred Wagner

  

No - both drives (I ordered two identical drives) were the same capacity as listed by the RAID controller in the "you idiot, this drive is too small to be used" screen.

At some point, I'll put both the old type of drive and the new drive in another computer and check them using a partition manager and see exactly what it says.

 

I ran into this once when I was trying to replace a hard drive in a machine I built for a DJ, 2 seagate 60GB ide drives on the motherboards raided ports, and one drive was reporting a failure, and unsynced the raid. I ordered another drive from NewEgg, and got the same model, but  since 3 years had passed, I got a different suffix, and it was about 12 MB too small, and would not sync the raid. When I checked the specs of the drives, the number of heads,sectors were different. I ended up having to repartition the drives so they had identical bytes,and then I could sync the drives in the raid.

  And here is the strange thing, I tested the drive I took out, the one marked bad by the array, by serial number. It passed, and I still have it, and all the mp3's that were on it, play just fine. I was never sure what caused the raid controller to hiccup and mark that drive bad.

Did you ever see my update on a thread I started way back regarding RAID??

http://www.tek-tips.com/viewthread.cfm?qid=1659496

 

the following explains it nicely, as to the C/H/S and how it is calculated...

btw. the differences could also stem from the fact that the older HDD (WD400BB) uses two platters and the newer one maybe just one platter...

 

Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

Nope missed it Goom, but that would explain some things, because I had to 750 Gb hdd supposed to be bad, from a failed raid 1 array from a Best Buy Geek Squad Beast PC, " the PC they save customer data to, if they need to muck around with a hard drive, or replace the drive or data. Anyways, this 750 GB drive works just fine outside of the array in a standard desktop, It has since been replaced by a WD RE drive.

BadBigBen - no linky

oh, man what happened to the LINK...

I hope this works now:

Disk geometry salad...
http://lists.freebsd.org/pipermail/freebsd-questions/2004-June/048133.html

also one should be aware of the following, as well:

WARNING! GB m/bs nab 2113 sectors of HD!
http://forums.whirlpool.net.au/archive/1479604
 

Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

That's all very interesting but it would have been nice if I could have looked at the drive reference material/specs and seen that there would less than 38166MB vs. the old drive.

I agree Goom, but to get the new drive to work with the old, you will now need to reduce the size of the older by the amount that the newer is smaller...

though some, not all, RAID controllers do this on the fly...

Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

What I meant was that it would be nice if the drive specs showed how much space was available so that you could do an exact comparison.

I know the ultimate solution for any of these issues is to buy one more drive than you need in order to have a spare on the shelf.

I knew what you meant, that is why I agreed... ;)

and we have a saying in Germany: "Doppelgemoppelt hällt länger...", roughly translates to "duplicity lasts longer..."

Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"