areca raid5 data corruption....

[gaspah]

OK, the other day.. i went to do an online migration to add 2 drives to my areca 6x400GBxRaid5 array.... but whilst physically connecting the 2 new drives i accidentally pulled the power from 1 of the hard disks already part of the array.. after realising what i had done i quickly shut down the pc, connected the hard drive went to rebuild.. but to my absolute HORROR... when i went back into windows, widespread data corruption had locked most of my folders and were only accessible through data recovery tools (r-studio), but even after grabbing those files too many were corrupted to try and sort them out.. i consider the volume a total loss.... now thankfully i backed up that 2TB to DVDs well >95% of it... so i managed to recover pretty much everything (even if it took a week to do) i only lost a little bit of music and a few save games...

now my question is, wasnt the whole freakin point of me getting raid5 to protect me from losing 1 drive?? isnt that the only advantage of raid5 over raid0?? i mean wtf?? I may as well be on raid0... this is bullshit... i bought supposedly an 'awesome' card, but that doesnt seem to mean shit.... so I'm thinking of just switching to JBOD... which is just the icing on the $750 areca arc-1220 cake....

 

[wasserkool]

I am sorry but why would you add a HD to your system while the system is POWERED ON? Unless you have a hot swap bay, i do not see why you should EVER install new HDs in a system with many drives while it is powered on. Even the RAID 5 (AMCC 9550) controller I use warn me against unplugging drives in array that are powered on unless I send the command through the CLI to swap the drive.

Unplugging a drive while its active is different than a HDD failure.

 

[gaspah]

I am sorry but why would you add a HD to your system while the system is POWERED ON? Unless you have a hot swap bay, i do not see why you should EVER install new HDs in a system with many drives while it is powered on. Even the RAID 5 (AMCC 9550) controller I use warn me against unplugging drives in array that are powered on unless I send the command through the CLI to swap the drive.

Unplugging a drive while its active is different than a HDD failure.

i was only going to unscrew the hdd cage while it was powered on (when the power cord was pulled).,. i was going to switch it off to actually install the drives to the array.. but yeah...

normally i never switch off to add sata drives.. ive never had a problem adding sata drives while the computer is switched on... infact at work i connect/disconnect sata drives to a live machine on average 15 times a day (ghosting sealed oem windows onto new pcs).. i thought that was the whole point of hotswap

and how is unplugging the power to 1 drive different than it failing??? please be specific??

 

[Fryguy8]

so wait, you disconnected a drive, and then turned off the computer? why? The areca will rebuild for you live.

Granted I have hotswap bays with the fail leds wired, but I must be missing something here. A hardware raid5 controller isn't going to just corrupt all of your data when a single drive fails in raid5.

 

[gaspah]

so wait, you disconnected a drive, and then turned off the computer? why? The areca will rebuild for you live.

Granted I have hotswap bays with the fail leds wired, but I must be missing something here. A hardware raid5 controller isn't going to just corrupt all of your data when a single drive fails in raid5.

well it did... it took me a week to recover from DVDs... folders were locked... some files appeared 0KB... some files appeared the right size but were corrupt and wont play... it was a complete nightmare.. i lost my save games permanently.. grrrr,....

and i wasnt even using the volume at the time... its not my system volume... and i wasnt accessing anything so i have no idea what on earth happened...

 

[wasserkool]

I think the problem here is you turned off the computer which removed any chances of the card rebuilding the array or falling into the redundancy mode. Hence i say it is different than drive failure.

When the power was yanked from the live array, the card will immediately detect one drive went offline and will either start to rebuild the array or kick into redundancy mode. But either process takes time and if the power is cut off without letting the card complete the process, data corruption will appear.

Lets say in a normal drive failure scenario, the users will not know unless the RAID card through the config sends user a e-mail or audible warning, but the user will not immediately switch off the power to the system and interupt the rebuild process.

 

[gaspah]

I think the problem here is you turned off the computer which removed any chances of the card rebuilding the array or falling into the redundancy mode. Hence i say it is different than drive failure.

When the power was yanked from the live array, the card will immediately detect one drive went offline and will either start to rebuild the array or kick into redundancy mode. But either process takes time and if the power is cut off without letting the card complete the process, data corruption will appear.

Lets say in a normal drive failure scenario, the users will not know unless the RAID card through the config sends user a e-mail or audible warning, but the user will not immediately switch off the power to the system and interupt the rebuild process.

thanks a lot for the info.. i have slightly more confidence in raid5.. but im still concerned.. thanks for taking the time to explain that to me... it kinda makes sense in my head now...

 

[SC385]

well, if you're still concerned about Raid5 then go with Raid6. Although I don't think Raid 6 would protect against what happened either.

 

[Ockie]

Arrays are not 100% failsafe. I've had arrays corrupted just like yours before.

Backups, backups, and backups... I cant stress it enough.

 

[gaspah]

well, if you're still concerned about Raid5 then go with Raid6. Although I don't think Raid 6 would protect against what happened either.

I was thinking JBOD not Raid6... jbod gives me an extra 400GB

QUESTION: if i lost one of the drives in a JBOD array, can i recover the rest of the disks in the array?? well most of the data, i understand some files may span 2 disks

if i lost the first drive in the array, can i recover the rest of the disks?

Arrays are not 100% failsafe. I've had arrays corrupted just like yours before.

Backups, backups, and backups... I cant stress it enough.

Lucky people stressed that to be in the past... or i could be on [H] front page... "pc freak murders entire neigbourhood after hard drive failure"

i was hoping raid5 would have stopped me having to spend last week copying my ~500 4.5GB backup dvds to my harddrive..

 

[SC385]

i was hoping raid5 would have stopped me having to spend last week copying my ~500 4.5GB backup dvds to my harddrive..

Geez... for what you spent on blank DVDs you could have bought 1TB drives for backup.

I'm glad you got most of your stuff back though. It sucks when you see people loose everything because they thought raid was a viable backup solution or could go without a backup solution.

 

[gaspah]

Geez... for what you spent on blank DVDs you could have bought 1TB drives for backup.

I'm glad you got most of your stuff back though. It sucks when you see people loose everything because they thought raid was a viable backup solution or could go without a backup solution.

oh i've lost plenty of data over the years.. im completely paranoid now... i database everything i backup and backup to dvd weekly...

500 x 4.5GB = 2250GB costing less than $150 and are more reliable with the way i store them never using them unless catastrophe strikes.
1TB HDD cost more than $150... and with 1TB you can lose it all at once, dvds you may lose a file or two or maybe an enitre 4.5gb disk but most will be there.

so anyone know about recovering JBOD????