Feeds

Sun tripling RAID protection

Another salvo in the fight against disk failure

Internet Security Threat Report 2014

Comment The RAID industry standard for storage is RAID-6, with recovery from a double drive failure. But it's not going to be good enough as disk capacities increase, prolonging failed disk rebuild times and so lengthening the window of unrecoverable failure if a third disk fails before the recovery from a double drive failure is complete.

This point is made by Adam Leventhal of Oracle/Sun's Fishworks in a blog. He says hard drive capacity roughly doubles every year but hard drive bandwidth is pretty constant, so it takes longer and longer to write data to fill up a drive.

Other things being equal, a 500GB drive will take twice as long to write as a 250GB drive. Suppliers are now producing 2TB drives, taking four times as long to fill with data as a 500GB drive; Leventhal implying that it will take about eight hours.

Assume 3TB drives are coming, then 4TB ones, and we're looking at 12 hours and 16 hours respectively for a rebuild of a full failed disk. Every added terabyte adds four hours to the rebuild time, half a day. That's increasing the chances a third drive will fail in the rebuild period for second and first failed drive rebuilds.

Leventhal has added triple-parity RAID to Sun's ZFS filesystem, calling it RAIDz3. He suggests calling it generically RAID-7 or RAID-8 might be silly. RAID-6 is often known as RAID-DP though, so RAID-TP would seem logical. Leventhal says it too could be superseded if disk capacities keep on growing.

That has to be logically true but, if the use of 3.5-inch disks switches over to 2.5-inch drives then that would reduce failed disk rebuild times. It would also likely increase the number of drives in an array, putting us back, roughly speaking, at square one.

Triple-parity RAID-Z will be included in the next major software release for Oracle/Sun's 7000 series sometime in the third quarter of this year; in other words, in a few weeks. It's not a first though - Avante Digital had a triple-parity EasyRAID product in 2006.

We might expect triple-parity RAID to start appearing, perhaps as an option, in mainstream enterprise EMC, HDS, HDS, IBM and NetApp arrays, and third-party RAID controllers from next year. ®

Top 5 reasons to deploy VMware with Tegile

More from The Register

next story
Docker's app containers are coming to Windows Server, says Microsoft
MS chases app deployment speeds already enjoyed by Linux devs
Intel, Cisco and co reveal PLANS to keep tabs on WORLD'S MACHINES
Connecting everything to everything... Er, good idea?
SDI wars: WTF is software defined infrastructure?
This time we play for ALL the marbles
'Urika': Cray unveils new 1,500-core big data crunching monster
6TB of DRAM, 38TB of SSD flash and 120TB of disk storage
Facebook slurps 'paste sites' for STOLEN passwords, sprinkles on hash and salt
Zuck's ad empire DOESN'T see details in plain text. Phew!
'Hmm, why CAN'T I run a water pipe through that rack of media servers?'
Leaving Las Vegas for Armenia kludging and Dubai dune bashing
Windows 10: Forget Cloudobile, put Security and Privacy First
But - dammit - It would be insane to say 'don't collect, because NSA'
Oracle hires former SAP exec for cloudy push
'We know Larry said cloud was gibberish, and insane, and idiotic, but...'
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Win a year’s supply of chocolate
There is no techie angle to this competition so we're not going to pretend there is, but everyone loves chocolate so who cares.
Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Saudi Petroleum chooses Tegile storage solution
A storage solution that addresses company growth and performance for business-critical applications of caseware archive and search along with other key operational systems.