It is not 100% safe to backup your data in DVD/CD. DVD and CD are made with chemical which corrords in-term of time and moisture. Blu-ray is 25GB and cost $25(my cost), $35(end-user) at this stage of time. It is more like $1/GB. And a blu-ray burner cost about $800. So far it is still not a very wise way to use for backups. Moreover, blu-ray is also made of chemical, although we do not know how long it could last. Remember, all the advertisement that says last forever or 100years achival, they are the answer to lab test. Unless you have a room that is free from moist and superb temperature to store your disc. The lab they use to test the media is definetely better then what our dry cabinet can do. We can't even stay 100years to witness that their test is truthful.
Storage Devices Poll and Discussions
- Thread starter microcosm
- Start date
RAID != Backup. Also: is doesn't need anything in BIOS for Software RAID.
Your explanation is a bit too simplified to be accurate. The idea is ok, but the purpose of RAID and Backup id entirely different.
It's an interesting discussion, indeed.
Before talking about "what to do" it is good to differentiate between "Backup" and "Redundancy". Redundancy is a concept to avoid "Single Points of Failure"; that means critical parts of a (IT) system are built in a way to overcome failures of single components (more or less) instantly. This keeps the system alive and ensures a higher availability compared to non-redundant systems. For storage (hard disks) the concept of RAID was developed. More can be read here: http://en.wikipedia.org/wiki/RAID
Backup means to keep several versions (='generations') of data for a certain period with the purpose to rebuilt the working data in case of a fatal data loss. Also, it allows "going back in time" to have the data at the moment of a certain time stamp. This concept has different requirements to the used technology, so RAID is not an option here. One important aspect is: once the data are written they must be protected from accidental changes. Otherwise the "going back in time" concept is violated. Because of the shorter retention period and economical reasons backup media are usable for multiple backups overwriting the older data. The protection against accidental changes is achieved by other means (software, organizational processes). Archiving must be safe from all kinds of alteration.
Another aspect is: how long do you want to keep your data? 1 year? 5 years? 10 years? Usually (IT Industry), backup data are kept for about 4 to 8 weeks. Afterwards they are replaced by copies of more recent data. But everything above 1 year retention period is considered as "archiving", not backup. Also important: the technology to create the backups and data archives must be available in order to read your backup and archive media and retrieve the data. This includes hardware (drives and interfaces), operating systems and hardware drivers, file systems and file formats.
The typical backup medias used in IT are tapes whereas forms of WORM media are used for archiving. Tapes have evolved to a pretty high capacity (DLT S4: 800GB per tape), but also require the respective drives which are not cheap. DLT IV stores 40GB per tape and the drives and tapes should be affordable by now. Alternatively, cheap WORM media can be used. WORM = Write Once, Read Many; which is basically what we know as CD/DVD-ROM. Another type of WORM are special Magneto-Optical Disks (MO-Disks) which are used for audit-save data archiving. The consumer MO-Disks are not WORM's but rather "external hard drives" with a write protection switch. There are MO types of 2.3GB capacity. But they all require a special drive. Fujitsu and Sony have this available (Sony users know it as "Mini Disk".)
The next aspect is the storage of your media. Tapes need certain environmental conditions, CD/DVD as well. Otherwise the chemical and physical processes happening inside will rapidly make them unreadable. Additionally, tapes should be kept away from all kind of electromagnetic radiation. All this can be achieved by storing them in dry cabinets and keeping the temperature at about 22 degrees.
MO-Disks are pretty robust, they can stand higher temperatures and also any kind of electromagnetic radiation. The casing provides good mechanical protection, too.
Conclusion: DVD's can be a cheap and easy way to backup and archive your data for the next couple of years. But you need to keep them in a safe place (dry cabinet). Since BluRay drives are CD/DVD-compatible the access to the backups should be safe for the next 5 years. Latest after this period you'll need to verify the media status and transfer the data to a newer media set. Be aware: some CD/DVD writers are quite inaccurate which may result in media being unreadable in other drives.
Tapes require some additional hardware but the technology is pretty mature by now and there are enough real-live data about how the tapes 'age' and how to handle them.
MO-Disks seem to be a good solution for long-term archiving but are more costly and require the special drives. There are some vendors of industrial media who give 30 years warranty for the media and the drives to be available. Consumer MO-Disks can be used but I'm not sure for how long the drives will be available and if they can read all older disks.
Other topics about file systems (FAT32, NTFS, ext2, ext3, HPFS and others) and file formats (jpg, jpeg, raw, png and others) appear to be less critical. There are plenty of tools available to convert older data into newer formats.
microcosm
Senior Member
Ha ha ha... how come never use mistress in your analogy? She usually is the one very loved and carry on the "seed" faithfully behind the scene? Like a RAID 5?
And we know RAID 5 and mistresses has the same quality : EXPENSIVE... ha ha ha
But HD's are horribly complex mechanical devices with very specific interface and electrical needs.
A CDR/DVDR is a piece of plastic with dyes in it.
Yes the dyes will fade, but so will the magnetic patterns on the HD, and to read back those magnetic patterns on the HD a complex piece of mechatronics has to operate 'just right'.
5-10 years from now, a 'current model' computer will probably still be able to read the CDRs. The interface specs for HDs will probably have changed again and Windows Vista 2015 use a different disk format
The ISO9660 format for CD's and the extension for DVDs is very simple, Microsoft's NTFS is very complex. More chance of being able to recover at least something from a damaged CD in the future than from a corrupted NTFS HD.
At the end of the day how is the longevity of the better quality CDR/DVDR going to compare with film anyway ?.
My work has 30 year old slides that are almost clear film now - the dyes have faded, they have 1000's of other slides in which the dyes have significantly faded - and not faded equally in all colours.
My last 10 years worth of Digital images are on a combination of CDR, DVDR and the RAID array on my office network. Every now and then I do another burn off the RAID array. My oldest couple of years of digital images are now on a DVD-R DL disk....
selamatlzh
Senior Member
Don't sounds right to me, does it gives you individual volume access or a no choice one 1TB (raid-0) volume ??
selamatlzh
Senior Member
Either or. 500gb on raid 0 and 1 terra as a volume, or u call this spanning of disk.
But HD's are horribly complex mechanical devices with very specific interface and electrical needs.
A CDR/DVDR is a piece of plastic with dyes in it.
Yes the dyes will fade, but so will the magnetic patterns on the HD, and to read back those magnetic patterns on the HD a complex piece of mechatronics has to operate 'just right'.
5-10 years from now, a 'current model' computer will probably still be able to read the CDRs. The interface specs for HDs will probably have changed again and Windows Vista 2015 use a different disk format
The ISO9660 format for CD's and the extension for DVDs is very simple, Microsoft's NTFS is very complex. More chance of being able to recover at least something from a damaged CD in the future than from a corrupted NTFS HD.
At the end of the day how is the longevity of the better quality CDR/DVDR going to compare with film anyway ?.
My work has 30 year old slides that are almost clear film now - the dyes have faded, they have 1000's of other slides in which the dyes have significantly faded - and not faded equally in all colours.
My last 10 years worth of Digital images are on a combination of CDR, DVDR and the RAID array on my office network. Every now and then I do another burn off the RAID array. My oldest couple of years of digital images are now on a DVD-R DL disk....
I guess if one keeps changing the media, i.e. from VCD - DVD - DLDVD - ?Blu-ray this may help offset the issue of the dye fading.
And if for whatever the reason, one stops doing it, then it prob means the pics were not worth keeping ...
selamatlzh
Senior Member
My equipment failed 2 months ago. It took them 50 days to recover my data.
Failed even on mirror mode.
microcosm
Senior Member
Oh crap! How much did that cost you?
Isn't this your backup storage ?
If this is your online storage, you should have another backup storage.
To me, a box is a box, if it failed, it failed, the weakest point is the box itself.
selamatlzh
Senior Member
It didn't cost me anything but wasted alot of my time, no access to ALL my data for 50 days.
They refuse to tell me the cause of the problem. Crab excuses like hard drive failure. They didn't change my enclosure.
I learn my lesson, this is right a box is still a box even running mirror is still a box. If the box die you loose everything. So now I have 3 box instead of one.
selamatlzh
Senior Member
I have not finished verifying all my data, this is very time consuming.
However I did a quick check on all my photos that I took in 2008 only 2 seems to be corrupted so this is not too bad. But is too early to tell.
However I did a quick check on all my photos that I took in 2008 only 2 seems to be corrupted so this is not too bad. But is too early to tell.
I experience office hard disk failure abt a year or 2 ago. HDD motor burned. Only solution is to send in for lab recovery. 40GB = $1600. Is lucky that the dont charge you for recovery or tell you things like HDD failure, we do a 1 to 1 exchange. I believe in ur case is 1 drive n box down but the other drive still working, otherwise, they will be crying for 500gb lab recovery..
Not sure if some of these have been mentioned, but missing the forums for too long - no external internet access for months.
I would suggest using SCSI HDDs, instead of plain old SATA HDDs. The former is more expensive for a reason - longer Mean Time Between Failure (MTBF) ratings. Of cause, it comes with the need for a more expensive enclosure, controller etc.
One of the practice I seen pretty often, but advice against, is to use external HDD, archive and store. Have seen and replaced too many failed HDDs just cause they are left idle for too long. If one uses external HDD as archive 'backup', keep them spinning.
For professionals, I would advice engaging offsite storage companies for your backup needs. There are online versions offered by some companies, though they do not come cheap. The premium paid comes with the peace of mind that the companies involved will do the necessary to recover the data when times comes. For those with tight budget, simple DVD backup and rotating (re-burn) them every few years (iirc, DVD have expected shelf life of 7 yrs; most claim 5yrs optimum). I won't advice CD-R, simply cause of the space available, and the vastly available inferior quality CD-R found in the market.
I would suggest using SCSI HDDs, instead of plain old SATA HDDs. The former is more expensive for a reason - longer Mean Time Between Failure (MTBF) ratings. Of cause, it comes with the need for a more expensive enclosure, controller etc.
One of the practice I seen pretty often, but advice against, is to use external HDD, archive and store. Have seen and replaced too many failed HDDs just cause they are left idle for too long. If one uses external HDD as archive 'backup', keep them spinning.
For professionals, I would advice engaging offsite storage companies for your backup needs. There are online versions offered by some companies, though they do not come cheap. The premium paid comes with the peace of mind that the companies involved will do the necessary to recover the data when times comes. For those with tight budget, simple DVD backup and rotating (re-burn) them every few years (iirc, DVD have expected shelf life of 7 yrs; most claim 5yrs optimum). I won't advice CD-R, simply cause of the space available, and the vastly available inferior quality CD-R found in the market.
I wouldn't say that is true any more. The big storage vendors now offer a choice of SAS (Serial Attach SCSI) or SATA drives. Often in the same enclosure - SAS and SATA are so close in spec now that the one controller can do both - the SATA drives having a simple passive 'interposer' circuit between them and the SAS bus.
They market on performance differentiation - the SAS drives are the 'performance' end, tend to have lower capacity but faster spindle speed (15k RPM typically). SATA are the lower performance end (10K spindle), slower data transfer but MUCH larger capacity.
My office Dell MD3000i array has both SAS and SATA drives in it. The SAS drives have a maxium capacity of about 400gb - the SATA drives are 1Tb. We wanted storage more than speed, so all the 'expansion' drives are SATA.
The Vendor (Dell) offers the same warrentee on both drive types. Possibly the SATAs fail more, I don't know, but I would actually expect the SAS drives to fail more often simply due to the somewhat higher speed they spin at.
The only difference between the SAS and the SATA version of the same capacity/spindle speed drive will be the chip that drives the bus. The rest of the electronics and the chamber will be identical.
It's possible the manufacturer puts the drives intended for the server market (both SAS and SATA) through more rigourus Q&A. On the other hand they may just be slapping 5 year warrentee stickers on them and hoping the higher sale price this gets will cover the cost of the returns.
Backup often and diversely.
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