Unlike in most of our cases, the SAN was still operational, even though it was operating extremely poorly. We approached this Dell EqualLogic data recovery case differently than a normal SAN or server data recovery case.
Updating hard drive firmware equallogic ps4100 windows#
Using Windows to establish first contact with the SAN Dell EqualLogic PS4100 Data Recovery: Unrecoverable read media error In this Dell EqualLogic PS4100 data recovery case, the client’s 24-drive RAID-50 had been divided into four 6-drive RAID-5 arrays, allowing four drives to fail. In terms of storage capacity, though, RAID-50 beats RAID-10. But it’s roughly equally as fault-tolerant as RAID-10 (which can withstand multiple drive failures, but might fail if two drives fail). It’s more fault-tolerant than RAID-5 (which absolutely will fail if two drives fail). So RAID-50, like RAID-10, can fail if two drives fail. If two drives from one sub-array fail, you’re toast. Your RAID-50 can lose as many drives as there are RAID-5 sub-arrays beneath the RAID-0 level-as long as only one drive from each sub-array fails. By striping these individual RAID-5 arrays together using RAID-0, you end up with a RAID-50. If you have several RAID-5 arrays, you can lose one drive from each array without any of them failing. Thanks to the use of parity bits, you can lose one drive in the array and keep going. In a RAID-50, you have several RAID-5 arrays, striped together like individual drives in a RAID-0 array. Another drawback of RAID-10 is that you only have half of the total capacity of all your drives. If two identical drives fail on either side of the mirror, the entire array crashes. RAID-10 has excellent fault tolerance-but only if certain drives fail. Then you mirror the RAID-0 array across an equal number of drives.
In RAID-10, you take several drives and stripe them into a RAID-0 array.
We have a bit of an explanation of how RAID-10 works here. RAID-50 takes RAID-5’s fairly good fault tolerance and RAID-0’s utter lack thereof and combines them into an array that usually has very good fault tolerance. It combines RAID-5 and RAID-0 together, much like how RAID-10 combines RAID-1 and RAID-0. Type of Data Recovered: ESXi virtual machines Situation: After 4 drives failed, RAID performance dramatically decreased and the SAN became unusable Dell EqualLogic PS4100 Data Recovery Case Study: 24-Drive RAID-50
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