Comments on: RAID 5 Video Demonstration: Salvaging Data with a Stale Drive

By: IBM Storwize Data Recovery Case Study: Storwize V3700 Server

IBM Storwize Data Recovery Case Study: Storwize V3700 Server — Fri, 18 Aug 2017 15:12:48 +0000

[…] Two of the RAID-5 arrays in this server had been running degraded for some time. In January, two drives in two separate RAID arrays had failed, and since then, both arrays had been running in a degraded state. The first drive(s) in a RAID array to fail are known as stale drives. As time passes and the degraded server continues its operations, the data trapped on the failed drives becomes increasingly out-of-date. Forcing stale data back into a RAID array causes massive data corruption. […]

By: VMWare ESXi VMFS Recovery Case Study: RAID-5 Failure | Gillware

VMWare ESXi VMFS Recovery Case Study: RAID-5 Failure | Gillware — Fri, 18 Aug 2017 14:34:31 +0000

[…] To access this failed RAID array’s VMFS filesystem, our RAID recovery technicians first had to rebuild the array. To do this, we needed the write-blocked images of the two healthy drives and the last drive to fail. While the first failed drive was also healthy, because its data was stale, introducing it into the rebuilt RAID would have been catastrophic. […]

By: VHDX Recovery Case Study: Risky RAID-5 Rebuild | Gillware Inc.

VHDX Recovery Case Study: Risky RAID-5 Rebuild | Gillware Inc. — Fri, 18 Aug 2017 14:04:13 +0000

[…] failed hard drives. Casting aside the replacement drive and the first failed hard drive (which was filled with “stale” data), Cody could rebuild the array using the two remaining drives. After using RAID controller […]

By: HP ProLiant Data Recovery Case Study: Yellow Means Caution | Gillware

HP ProLiant Data Recovery Case Study: Yellow Means Caution | Gillware — Thu, 17 Aug 2017 21:09:09 +0000

[…] Servers typically connect hard drives together using fault-tolerant methods, such as RAID-5. A RAID-5 array has one drive’s worth of fault tolerance, meaning one hard drive can fall offline without jeopardizing the client’s data. Servers are meant to run continuously, so they constantly monitor the health of the hard drives in the array. If the RAID controller senses that one drive is behaving oddly or about to fail, it will kick the drive offline and let the RAID array’s fault tolerance on the remaining two drives fill in for it. Because the drive is offline for months, the data on it becomes out-of-date and “stale”. […]

By: RAID Recovery Case Study: RAID 5 Failure and Reconstruction | Gillware

RAID Recovery Case Study: RAID 5 Failure and Reconstruction | Gillware — Thu, 17 Aug 2017 21:07:54 +0000

[…] can look at our video blog post to find out what happens when you try to reconstruct a RAID 5 array with a stale…. The results aren’t particularly pretty. The stale blocks of data can cause massive amounts of […]

By: Dell T420 Data Recovery Case Study: "State Foreign" Error | Gillware Inc.

Thu, 17 Aug 2017 19:58:09 +0000

[…] Putting the server back together only required one of the two failed drives, though, due to RAID-5’s parity. This is good, because when two drives fail, they rarely do so at the same time. As a result, the first drive to fail ends up filled with “stale” data, which we want to avoid using to repair the RAID array as long as we have a choice in the matter. […]