Disk-to-disk Backup to Storage Service Provider

Earlier Days

Since the earliest days of computer technology, our forefathers (in Internet time) had to cope with computer breakdown (loss of data) differently that what we have to face today.

Believe it or not, from a study conducted by University of California at Berkeley stated that we (human) will create more data in the next three years than the data that we've created in the last 40,000 years.

I just heard this today and realized that it might not be entirely false. This is why:
1. Regulatory compliance for companies to store much more data - HIPPA, SOX, ISO 17799, and more.
2. Explosive data growth in consumer realm - digital cameras, digital video cameras, and more.
3. Increasing value of data especially ones created in the consumer realm - people are attached to what they created - digital pictures, digital arts...

Punch Card, Magnetic Tape, And Disk as Backup Media

Today we'll talk about Backup technology. Since the early days of computer, we learned to keep the backup data media in a vault somewhere in the case that we need to retrieve them. In 1950s, we learned to keep punch cards (kids these days may have never heard) in a vault. But these cards are made of paper. So it's likely that it could be eaten by insects, destroyed in the fire, or damaged by humidity/time. Shortly after punch-card, magnetic tape came into the picture in 1951 to be used as backup starting from the Univac that we all know. Since then our world of backup remains the same by relying on magnetic tape or tape cartridge or tape media.

When i mention that it remains the same, i mean every large corporations rely on tape as a single backup media/strategy. What most people don't know is the reliability for the tape backup system remains not much higher comparing to when it started.

Tape backup system's SLA (Service level agreement) remains at 77%. Or you can not restore approximated 23% of the time. This fact is unknown to most of the IT world. The reason that it fails 23% of the time is caused by the fact that tape media could be moved. 23% could come from human errors (losing the tapes, putting the wrong tape to restore, etc), media errors (tape media is always deteriorating because of heat and humidity), and other configuration errors.

Hard drive is still the only high SLA (99.99%) storage media in the world. Currently hard drive price is declining. Many backup software vendors now start to look at storage as an alternative. This is the beginning of disk-to-disk backup.

Disk-to-disk Backup Format

Disk-to-disk backup means that you backup your data from disk(primary storage) to another disk(secondary storage). While primary storage (FC-AL) price are normally much higher than secondary storage (iSCSI).

The question is that when you do disk-to-disk backup, does it mean that you have two drives with the same data? The answer is no. Backup software vendors support different formats. For example, Veritas NetBackup (now owned by Symantec) supports GNU tar format. Since GNU tar file format supports compression and encryption as standard. Veritas could extend these feature (compress, encrypt) to its products. Veritas BackupExec not only support tar format, it can also support straight volume copy (flash backup) such that end user can grab the targeted file from the backup disk pool.

Suitable HDD Technology with Disk-to-Disk Backup

Since disk-to-disk backup utilizes a large pool of storage, expensive hard drives (Fiber-Channel, SCSI) are not suitable. ATA (P-ATA), SATA or even SAS drives are better matches. As i've discussed about the seek time, transfer time comparison between FC-AL HDD and SATA HDD. Both SATA HDD (5-7ms seek time), FC-AL HDD (1-3ms seek time) have similar transfer time characteristic. D2D is normally a sequential read or write (read while restore, write while backup). So using SATA HDD in D2D application will not cause much performance impact comparing with FC-AL HDD.

What Else Is In Store For Disk-to-Disk Backup?

Since SATA HDD is the suitable hard drive technology. Most SATA drives are offered with iSCSI systems. SATA Storage + iSCSI technology enables D2D backup through IP network. So what's next in store for D2D is the ability to send backup traffic off-site through IP to another IP storage in another data center across the country.

So SMBs ,that do not want to buy their tape backup system and maintain their backup server, have the choice to call the storage service provider (backup recovery service provider) near them. This provider could be all the way across the country (east coast-> west coast in the U.S.). However, multi-country backup recovery service providers do not exist today due to international bandwidth costs much more than domestic bandwidth. Storage service providers are normally serving customers within a country (Verizon, AT&T, MCI, BT)

The storage service provider that I have the priviledge to work closely with is True Corporation. We've gone through the good part of 2005 together from inception to Storage service market. Now we're signing up customers in a bus load. True owns majority of fixed line in Bangkok, third-largest mobile operator, largest pay-tv operator, largest broadband provider, largest IDC in Thailand.