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Old 03-06-2018, 04:07 PM   #14
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Join Date: Nov 2011
Posts: 2,302
Default Re: How many uf do i need to cope with the HDD inrush current

Originally Posted by eccerr0r View Post
SATA (and of course SAS) are indeed capable of hot plugging. However the OS and the protocol may not.
Yes. And I am not confident in the sorts of testing that goes into the various implementations that you might come across "in the market".

I (almost!) had a complete data loss experience exactly once. I updated my OS (FreeBSD, at the time, IIRC) and mounted an external 4G SCSI drive (back when 4G drives were $1K -- if you bought *10*!). Jibberish!

<frown> "Well, that was a crappy $1K investment!"

Replaced drive with the cold spare that has identical contents (like half of a cold RAID1). ALSO jibberrish!

Hmmm... can't believe two drives that have been sitting on a shelf both decided to fail at the same time! Sure as hell am not going to try any of the other identical drives until I make sure there isn't something wonky with the cabling, enclosure, power supply, etc.

Nope. But, discover there's a problem with the updated driver (which doesn't affect the IDE boot drive)!

Roll back to previous version of OS. Drag out third copy of the data (on MO media) and manually restore first two drives using that.

I have a 4-bay bare drive "dumb" SATA hotswap bay and the power connectors are a weak point, they need to be strengthened.
Most folks think connectors "work forever". What they don't realize is how FEW insertion cycles many are actually rated! (Of course, a rating doesn't mean that the connector catastrophically FAILS when that limit is exceeded; but, all bets are off as to what you can reliably expect!).

For example, many DIMM connectors are rated for *6* cycles. SATA connectors for 50.

If the failing connector is part of a wiring harness, you're in luck: replace the wiring harness and you're starting with a fresh "quota" of insertion cycles! OTOH, if the connector is on the actual device...

Yes, I need my caffeine, or rather need to make sure I'm not asleep doing this hot swap surgery; one false move minimally means a reboot and of course worst case is data loss if I pull the wrong drive or down the wrong disk.
Ohnosecond: noun; the time between commanding your finger to strike the ENTER key and realizing you shouldn't have done that; usually a wee bit less than human reaction time...
Curious.George is offline   Reply With Quote