Data Recovery in RAID 1 and RAID 5 for AS5304T

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PHKahn
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Data Recovery in RAID 1 and RAID 5 for AS5304T

Post by PHKahn »

In choosing between Raid 1 and Raid 5 configuration for the AS5304T, I would like to know that once my volume is degraded due to a single disk failure, can I access my data to copy it to a backup drive before attempting to rebuild the volume on a replacement drive? My understanding is that while I am rebuilding the replacement drive, my volume is not available (for both Raid 1 and Raid 5). Is this correct? I have read that rebuilding can take a long time (days), and I do not want to be locked out of access to my data if possible.

Thank you,

Philip
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father.mande
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Location: La Rochelle (France)

Re: Data Recovery in RAID 1 and RAID 5 for AS5304T

Post by father.mande »

Hi,
PHKahn wrote:In choosing between Raid 1 and Raid 5 configuration for the AS5304T, I would like to know that once my volume is degraded due to a single disk failure, can I access my data to copy it to a backup drive before attempting to rebuild the volume on a replacement drive? My understanding is that while I am rebuilding the replacement drive, my volume is not available (for both Raid 1 and Raid 5). Is this correct? I have read that rebuilding can take a long time (days), and I do not want to be locked out of access to my data if possible.
Thank you,
Philip
As I know ... Raid fail in "degraded mode read only" when you lost ONE (and only ONE) disk
... so it's always possible to read data (so backup it)
... Raid 1 rebuild is always shortest ... because it's a copy, Raid 5 data are per block (not per file) with checksum (need to rebuild) distributed on all disks of the Raid5

Philippe.
AS6602T / AS5202T /AS5002T / AS1002T / FS6706T
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orion
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Re: Data Recovery in RAID 1 and RAID 5 for AS5304T

Post by orion »

mm... I have a different opinion. When in degrade mode, you can still read/write data. I actually tried that before.
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father.mande
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Joined: Sat Sep 12, 2015 2:55 am
Location: La Rochelle (France)

Re: Data Recovery in RAID 1 and RAID 5 for AS5304T

Post by father.mande »

Hi,
orion wrote:mm... I have a different opinion. When in degrade mode, you can still read/write data. I actually tried that before.
Fortunately, I don't have lot of experience in breaking raid ...

If I can understand for Raid1 (working by copy at file level) that writing on is not a stooping action, I have a little more doubts for Raid5 due to the method (write block on each disk and checksum for recovery)
... it's my only experience ... when I rebuild my Raid5 and one time ... so my expertise is reduce.

... so you are perhaps true :D

Philippe.
AS6602T / AS5202T /AS5002T / AS1002T / FS6706T
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