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Hard Drive Bible Notes

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Hard Drive Bible Notes

Never install 7,200 RPM drives as OS or Database Drives

Never create a 3 Drive RAID 5 (Even with 15k Drives)

Never create a 4 Drive RAID 5 with a host spare (This is a 3 Drive RAID 5)

Never create a 4 Drive RAID 5 with 10k or 7.2k Drives

Always opt for 3.5” drives over 2.5” drives (3.5” 15k drives cost the same as 10k)

15K Drives are 110% faster than desktop drives, 10K drives are only 40% faster

Always add all Disks to your RAID then create LUNS to partition the data

IOPs = ((RPM/1000)/(Latency*Seek))*SPINDLE COUNT

 

Average IOPs

  • 7,200 RPM = 75-100 (75 avg.)
  • 10,000 RPM = 100-150 (125 avg.)
  • 15,000 RPM = 150-200 (175 avg.)

 

Never use RAID 6 or RAID 5 in Write Intensive Applications

RAID 6 has the Highest I/O Write Impact, RAID 5 Second Highest

 

I/O Impact

  • RAID 0 – 1:1
  • RAID 1 /10 – 2:1
  • RAID 5 – 4:1
  • RAID 6 – 6:1

 

32 Cores, 192 GB of Ram and a 3 Drive RAID 5 with ANY drives = FAIL

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One thought on “Hard Drive Bible Notes”

  1. Don’t forget that read errors (URE) affect RAID more than most people think.
    If we were to lose a single drive, and any of the surviving drives experience an unrecoverable read error (URE), the entire array will fail.

    http://forums.storagereview.com/index.php/topic/34094-is-raid-56-dead-due-to-large-drive-capacities/

    As drives increase in size, any drive failure will always be accompanied by a read error. So RAID 6 will give you no more protection than RAID 5 does now, but you’ll pay more anyway for extra disk capacity and slower write performance.

    http://www.lucidti.com/zfs-checksums-add-reliability-to-nas-storage

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