When to replace hard drive in a RAID array
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If you have the space, back the data up to another location and blow away the RAID 5, toss the sick drive, rebuild into a RAID 10. Far less risk that way vs. add a new drive and pray that it rebuilds, plus no extra disks needed. The sooner the better on making a new array, I don't know if I would risk replacing a drive in a RAID 5 array (I'm making the assumption that these are 1TB + drives, which means that you have about as much chance of a successful rebuild as you have of getting hit by lightning).
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@Texkonc I have one in stock already, and I agree with you and @DustinB3403 it would be wiser to go ahead and take care of this now. Especially since I don't have a solid idea of when I can get to the project of getting off the RAID 5.
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@EddieJennings said in When to replace hard drive in a RAID array:
@Texkonc 3 TB (WD Red)
Ouch... if you try to rebuild that array and it works (don't hold your breath), I'd go out and buy a ticket to every lottery you can, because you'll never have that kind of luck again.
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NOW is the time to move to something other than RAID 5. The most dangerous thing that you can do is replacing that drive. Even once it fails, you don't replace it. Whoever designed that system made the decision that a failed drive meant moving off of the NAS when they installed it (you should explain this as an existing decision to management.)
The time that data gets lots is in the resilver.
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That's a 12TB failure domain on 5400RPM consumer drives. The resilver options will take days and the chances of success are way below 50%. So any drive replacement means you INTEND for all data on the array to be lost. You easily might get lucky and survive. But chances are, you won't. So only replace that drive if you plan for days of downtime, and then at a random point during those days of outage to have all of the data be lost.
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@RojoLoco said in When to replace hard drive in a RAID array:
@EddieJennings said in When to replace hard drive in a RAID array:
@Texkonc 3 TB (WD Red)
Ouch... if you try to rebuild that array and it works (don't hold your breath), I'd go out and buy a ticket to every lottery you can, because you'll never have that kind of luck again.
I had StoreVirtual dual node SAN with 24 4TB drives take 7.5 days to repair without issue or popping another drive. Raid 6 thankfully though.
Edit: Thankfully I got Dev/QA to approve shutting down servers for a week that would not be need to lessen the load. Might have been bad times if I didnt. -
@Texkonc said in When to replace hard drive in a RAID array:
@RojoLoco said in When to replace hard drive in a RAID array:
@EddieJennings said in When to replace hard drive in a RAID array:
@Texkonc 3 TB (WD Red)
Ouch... if you try to rebuild that array and it works (don't hold your breath), I'd go out and buy a ticket to every lottery you can, because you'll never have that kind of luck again.
I had StoreVirtual dual node SAN with 24 4TB drives take 7.5 days to repair without issue or popping another drive. Raid 6 thankfully though.
I don't know if I could handle 7.5 days without sleep!
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@scottalanmiller The chance of failure on the resilver is what frightens me, which, contrary to what I posted a couple of minutes ago, makes me want to make the drive swap happen when I redo the RAID as RAID 10. For that matter, I'll also look and see what the cost would be to add drives to the server that connects to the NAS via iSCSI and just have the data stored locally.
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@EddieJennings said in When to replace hard drive in a RAID array:
@scottalanmiller The chance of failure on the resilver is what frightens me...
That's why to deal with the whole thing now. Consider it an emergency situation.
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Wealth of knowledge has been gained in the last few minutes -- in particular how long it would take to resilver an array, which puts into perspective how dangerous RAID 5 is.
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@RojoLoco said in When to replace hard drive in a RAID array:
If you have the space, back the data up to another location and blow away the RAID 5, toss the sick drive, rebuild into a RAID 10. Far less risk that way vs. add a new drive and pray that it rebuilds, plus no extra disks needed. The sooner the better on making a new array, I don't know if I would risk replacing a drive in a RAID 5 array (I'm making the assumption that these are 1TB + drives, which means that you have about as much chance of a successful rebuild as you have of getting hit by lightning).
^ this exactly. Order larger drives today if you have too little space after RAID10 conversion.
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@RojoLoco said in When to replace hard drive in a RAID array:
@Texkonc said in When to replace hard drive in a RAID array:
@RojoLoco said in When to replace hard drive in a RAID array:
@EddieJennings said in When to replace hard drive in a RAID array:
@Texkonc 3 TB (WD Red)
Ouch... if you try to rebuild that array and it works (don't hold your breath), I'd go out and buy a ticket to every lottery you can, because you'll never have that kind of luck again.
I had StoreVirtual dual node SAN with 24 4TB drives take 7.5 days to repair without issue or popping another drive. Raid 6 thankfully though.
I don't know if I could handle 7.5 days without sleep!
Trust me, I woke up some nights to see if my VPN was still up. (an RRAS VM) then log into storage and check the percent complete.
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@EddieJennings said in When to replace hard drive in a RAID array:
@scottalanmiller For that matter, I'll also look and see what the cost would be to add drives to the server that connects to the NAS via iSCSI and just have the data stored locally.
That would likely make way more sense.
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Yeah they're still going to be of the same quality (NAS drives) but you'd be in a non-parity array.
Adding more drives would be a boost if you can fit them in as the entire system will operate that much more quickly.
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@Texkonc said in When to replace hard drive in a RAID array:
@RojoLoco said in When to replace hard drive in a RAID array:
@Texkonc said in When to replace hard drive in a RAID array:
@RojoLoco said in When to replace hard drive in a RAID array:
@EddieJennings said in When to replace hard drive in a RAID array:
@Texkonc 3 TB (WD Red)
Ouch... if you try to rebuild that array and it works (don't hold your breath), I'd go out and buy a ticket to every lottery you can, because you'll never have that kind of luck again.
I had StoreVirtual dual node SAN with 24 4TB drives take 7.5 days to repair without issue or popping another drive. Raid 6 thankfully though.
I don't know if I could handle 7.5 days without sleep!
Trust me, I woke up some nights to see if my VPN was still up. (an RRAS VM) then log into storage and check the percent complete.
This is why I keep a bottle of Pepto + sleeping pills in my tech emergency kit.
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When I started at my current place, we had an 8TB OBR5 with a failed disk, and our MSP didn't even notice it during maintenance...
How they weren't fired immediately I have no clue.... restoring the entire thing would've ticked me off to no end. We got super lucky and the resilver completed without issue. Something like 23% chance of success... . .
This system is now gone..
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What is your storage footprint like? % used/free.
Can you buy a two bay synology for under $200 on amazon and get some drives for it, copy your stuff there and blow away?
Remember you cant have 5 drives in R10, with your setup at least.
2 pairs of the 3tb drives, so you only get 6TB then a hotspare, but the space you loose. So think of that.. Will you need larger drives? What is your growth like? -
@Texkonc Yeah, I know I can't have 5 in a RAID 10. Currently we're using under 500 GB of this storage, so losing that drive isn't significant. Once my current two hair-on-fire esque tasks are done, I'll get on figuring out the procedure.
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@EddieJennings said in When to replace hard drive in a RAID array:
@Texkonc Yeah, I know I can't have 5 in a RAID 10. Currently we're using under 500 GB of this storage, so losing that drive isn't significant. Once my current two hair-on-fire esque tasks are done, I'll get on figuring out the procedure.
Only 500GB!
Go to staples now and buy a 1TB external and move the data off of this array.
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@EddieJennings And growth? 500 GB in about 6 years (which I believe is the age of the NAS and its drives).
