Hot Swap vs. Blind Swap
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True story. Right after I posted that last post, I went into the server room to take a picture of this paper good luck charm. On the way back down the hall, the building's power went out, and has been out the past 3 hours. This week is just AWESOME!
Anyway, here is the picture:
Note the failed DELL right below it.
It did its job for many years, though. No complaints.
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P.S. If anyone can read that, and it DOESN'T say good luck, please don't let me know.
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What the heck is that thing?
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@Reid-Cooper said:
What the heck is that thing?
Which thing?
The paper thing?
Way back in the day when I used to assemble computers, the wife of the guy whose shop I went to made that for me and said it was a good luck charm. I hung it in our server room, and it's been with the servers ever since.
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@BRRABill said:
P.S. If anyone can read that, and it DOESN'T say good luck, please don't let me know.
@JaredBusch might know.
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@scottalanmiller said:
RAID 5 induces other failures when you go to rebuild. It's extremely common and just an artifact of that RAID level. Doesn't mean that it will always do it or even normally do it, but it is very common. Once you do a drive swap it immediately increases the load on the drives and makes them more likely to fail.
Is it just RAID 5 that induces failures? I mean, theoretically couldn't a RAID 10 array do the same thing?
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@BRRABill said:
Is it just RAID 5 that induces failures? I mean, theoretically couldn't a RAID 10 array do the same thing?
Parity RAID induces it on resilver, mirrored RAID really does not. It does a little, but only a little, and only to a single drive not all drives. So the impact of parity rebuilds is always at least double that of any mirrored RAID and often many, many times more.
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My drive failed almost immediately. I mean, whatever happened rebooted the server.
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@BRRABill said:
My drive failed almost immediately. I mean, whatever happened rebooted the server.
With RAID 5 that can be almost anything. Secondary drive failed naturally, resilver induced, URE, etc. RAID 5 has abundant failure modes that could have happened there.
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@BRRABill It's possible that the drive had a loose connection and replacing the other knocked it offline.
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That too, could be as simple as physical vibration.
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@BRRABill That Chinese character means "Spring".
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It was firmly plugged in. I think it just gave up the ghost.
I've seen that kind of stuff happen with a surge, but that seems unlikely in a hotplug backplane.
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@drewlander said:
@BRRABill That Chinese character means "Spring".
Maybe she gave it to me in the Spring.
THOUGH...if all my server die tonight, I am blaming you.
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@BRRABill said:
My drive failed almost immediately. I mean, whatever happened rebooted the server.
Go right ahead. Did that drive fail after replacement while it was in a degraded state? Id say your controller is failing if that happened.
On a side note, I pretty much only use RAID 1 mirror w 1 hot spare (3 disks total) these days in what I do. The apps I deal with and code for (mostly) are OLTP with tons of tiny write transactions. Using a small stripe size and only two disks, this setup benchmarks 13x faster write speeds for me than a RAID5 array with 4 disks, all day, according to AS SSD. The way we coded our software and designed the database everything uses GUID's for PK. GoDaddy premium dns provides round-robin load balancing ( I don't manage that part). In Proliant servers (dl360 G7 for example) I like to install both backplane kits and split the RAID1 mirror between backplanes. This is just to show as example that there's really not a one-size-fits-all solution for server configurations and redundancy. The software I develop (or run) dictates what I am able to do with the hardware.
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@drewlander said:
On a side note, I pretty much only use RAID 1 mirror w 1 hot spare (3 disks total) these days in what I do.
Never use a hot spare with RAID 1 unless your controller really lacks basic functionality. Instead go to a triple mirrored RAID 1. This is far safer than RAID 1 with a hot spare because instead of needing to rebuild while lacking mirroring the data is always hot and ready AND you get a 50% read performance boost for the life of the array. So faster and safer, no downsides.
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@Jason said:
@BRRABill said:
P.S. If anyone can read that, and it DOESN'T say good luck, please don't let me know.
@JaredBusch might know.
The Japanese meaning for that is spring when used by itself. compounded with other kanji, the meanign could change.
Chinese reads the kanji differently. No idea on that.
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@drewlander said:
Go right ahead. Did that drive fail after replacement while it was in a degraded state? Id say your controller is failing if that happened.
There were 4 drives.
1 2 3 4
2 was degraded/failed. I took it out, and put in a fresh one. The server then rebooted, and both 1 and 2 showed up as failed when it came back up.
