RAID 5 resilver (rebuild) has the potential to take quite a long time.  The warm spare will not assist in protecting the array until this resilver process completes successfully – this is commonly many hours and is easily days and possibly weeks or months depending on the size of the array and how busy the array is.  If we took that same warm spare drive and instead tasked it with being a member of the array with an additional parity stripe we would achieve RAID 6.  The same set of drives that we have for RAID 5 plus warm spare would create a RAID 6 array of the exact same capacity.  (Thus never use raid5+hotspare, instead use Raid6) (the difference is power consumption and wear on the drive) Extrapolating to RAID6, a warm spare must justify itself against a RAID 10 array which is more performant and far more reliable than a RAID6 but more costly. In some cases, such as a small five disk RAID 6 array with a warm spare, this is dollar for dollar equivalent to a six disk RAID 10 array without a warm spare. In larger arrays the cost benefit of RAID 6 does become apparent but the larger the cost savings the larger the risk. -- gadget

Looks cool. But too big to carry. -- gadget

Great blog post. Fixed my Nikon Coolpix Lens Error by holding down OK button while powering on. -- gadget

Electromagnetic Rust Protection -- gadget

Which is better: RAID5 + 1 Hotspare / RAID6? -- gadget

The responses I received from Synology, QNAP, NETGEAR and Buffalo all indicated that their NAS RAID controllers don't depend on or even listen to TLER, CCTL, ERC or any other similar error recovery signal from their drives. Instead, their software RAID controllers have their own criteria for drive timeouts, retries and when a drive is finally marked bad. -- gadget

If you have a RAID 5 array, using 7 drives (no hot spare). With 2TB drives, then you have 12TB of data and 1TB of parity. When one drive fails it must read 12TB worth of data (even the empty data) to create the new drive information. Now, you run into the possibility of having a read error. Prior to the rebuild you didn't notice read errors because of the parity. However, during a recover operation, there is no redundant data. -- gadget

No enterprise storage vendor now recommends RAID 5. SATA drives are commonly specified with an unrecoverable read error rate (URE) of 10^14. When a drive fails in a 7 drive, 2 TB SATA disk RAID 5, you’ll have 6 remaining 2 TB drives. As the RAID controller is reconstructing the data it is very likely it will see an URE. At that point the RAID reconstruction stops. (1 - 1 /(2.4 x 10^10)) ^ (2.3 x 10^10) = 0.3835 , thus you have a 62% chance of data loss due to an uncorrectable read error on a 7 drive RAID with one failed disk, assuming a 10^14 read error rate and ~23 billion sectors in 12 TB. -- gadget

LCD on the front, EINK on the back. -- gadget

The World's first consumer-ready OLED lamp. (from OTI Lumionics) -- gadget

General Wi-Fi Borescope from Lee Valley Tools lets you see into small places. Works with Apple and Android devices. -- gadget

A proof-of-concept for playing tabletop role-playing games (D&D) on the Microsoft Surface Table. -- rpg, gadget