Q. I'm trying to understand the difference between recovery via reprocessing and recovery using rollbacks. My book doesn't do a very good job of describing the topic.
Is reprocessing used for restoring an entire database, where rollbacks are more for reversing a bad transaction?
Do both techniques require the use of database save, and if so...why does a roll back need a DB save for something as small as reversing one bad transaction. It just doesn't seem like you'd need to restore the whole DB just to undo one transaction.
Is reprocessing used for restoring an entire database, where rollbacks are more for reversing a bad transaction?
Do both techniques require the use of database save, and if so...why does a roll back need a DB save for something as small as reversing one bad transaction. It just doesn't seem like you'd need to restore the whole DB just to undo one transaction.
A. It is a big subject, but lets see if I can get you in the right frame of mind for it.
First a bit of history :-
Backing up a database was always trouble. You could do one of the following
.Back up all data and database code in one backup.
..This has the potential to be large, but many times the code will not change
..so is wasted space on the backup medium (tape, external drive)
..But it does mean that changes in code are copied with the database version
..it is for. Example tax changes in accounts were often hard coded (before the
..days of rules based databases).
.Backup data and code seperately.
...Better for size, less waste on the backup medium.
...Have to have a system to ensure the wrong code can not be used,
...for example table changes might mean old code can not be used with this data.
I have to say that nearly all that I was part of and saw in other companies was of the sort 'Back up code and data together'. It is a longer backup and recovery, a bit wasteful of space. But one (or one set) of tapes is all you need for a full recovery.
That is 'Reprocessing', i.e. refering to the actions needed to recover the data,
Rollbacks are very different. You still have backups (obviously) but you also have Archieves.
Now there is more than one type of Rollback.
You might offer a data rollback so that the users can look at old versions of the data, not the same as a history search, because this old data may need different code to run, might have changes in the fields. Back to accounts, in the UK you have to keep a full set of Accounts available for 8 years. The code of the accounts will almost certainly change each year (as soon as the chancellor has done his budget speach). The Rollback not only gives the user access to the old data, but processes it in the same way as stored in the archieve, the same tax rules etc.
If anyone ever talks to you about a Rollback that is destructive to the current data or code of a database, slap them. You will find this in text books as an option, but you never do it. There was a time when there was no choice, because of size limitations on servers, so you would backup the current, then recover to the rollback point.But not now, drives are cheap, even a spare server is cheap, never a need to do destructive rollbacks.
First a bit of history :-
Backing up a database was always trouble. You could do one of the following
.Back up all data and database code in one backup.
..This has the potential to be large, but many times the code will not change
..so is wasted space on the backup medium (tape, external drive)
..But it does mean that changes in code are copied with the database version
..it is for. Example tax changes in accounts were often hard coded (before the
..days of rules based databases).
.Backup data and code seperately.
...Better for size, less waste on the backup medium.
...Have to have a system to ensure the wrong code can not be used,
...for example table changes might mean old code can not be used with this data.
I have to say that nearly all that I was part of and saw in other companies was of the sort 'Back up code and data together'. It is a longer backup and recovery, a bit wasteful of space. But one (or one set) of tapes is all you need for a full recovery.
That is 'Reprocessing', i.e. refering to the actions needed to recover the data,
Rollbacks are very different. You still have backups (obviously) but you also have Archieves.
Now there is more than one type of Rollback.
You might offer a data rollback so that the users can look at old versions of the data, not the same as a history search, because this old data may need different code to run, might have changes in the fields. Back to accounts, in the UK you have to keep a full set of Accounts available for 8 years. The code of the accounts will almost certainly change each year (as soon as the chancellor has done his budget speach). The Rollback not only gives the user access to the old data, but processes it in the same way as stored in the archieve, the same tax rules etc.
If anyone ever talks to you about a Rollback that is destructive to the current data or code of a database, slap them. You will find this in text books as an option, but you never do it. There was a time when there was no choice, because of size limitations on servers, so you would backup the current, then recover to the rollback point.But not now, drives are cheap, even a spare server is cheap, never a need to do destructive rollbacks.
NTFS Hard drive recovery software? i was looking for Shareware/Freeware.?
Q. Last night my second hard drive crashed and All the information was deleted (i know not really deleted) but the indexing was erased... I found the files using some buy now software that lets you look before you buy, and it;s there, but i don't want to pay 100.00 for it, has anyone found some freeware/shareware that will do it, or if i have to i can buy some, but the cheaper ther better.
Let me say this again, i found plenty of software to buy $$$$$$$$$, I am not looking for that.. I'm looking for a NO COST OPTION.
Thanx for all your input...
Let me say this again, i found plenty of software to buy $$$$$$$$$, I am not looking for that.. I'm looking for a NO COST OPTION.
Thanx for all your input...
Let me say this again, i found plenty of software to buy $$$$$$$$$, I am not looking for that.. I'm looking for a NO COST OPTION.
Thanx for all your input...
Let me say this again, i found plenty of software to buy $$$$$$$$$, I am not looking for that.. I'm looking for a NO COST OPTION.
Thanx for all your input...
A. Edit: Well, you want freeware, huh, but be careful though. Some of this freeware could damage your hard disk or damage your data even further as not all of them perform as they've claimed.
You'd do well to ask everyone how much experience they've had with the software they've suggested, then.
For commercialware: Spinrite is pretty good.
For freeware, PC inspector file recovery at http://www.pcinspector.de/file_recovery/uk/welcome.htm
(Yep, I just tried this software which seems to work quite well. There was this archive about 300++ mb huge that I'd deleted a few hours ago. And it also recovered loads of files I'd deleted up to a few weeks ago! )
You'd do well to ask everyone how much experience they've had with the software they've suggested, then.
For commercialware: Spinrite is pretty good.
For freeware, PC inspector file recovery at http://www.pcinspector.de/file_recovery/uk/welcome.htm
(Yep, I just tried this software which seems to work quite well. There was this archive about 300++ mb huge that I'd deleted a few hours ago. And it also recovered loads of files I'd deleted up to a few weeks ago! )
Are these good specs for a very cheap PC?
Q. Motherboard
EVGA 123-YW-E175-A1, NF750i SLI, 775, PCI-E (x16), DDR2 1066/800, SATA II, SATA RAID, ATX
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=801000
CPU
Intel Core 2 Duo E6750, Conroe Core, S775, 2.66 GHz, 1333MHz FSB, 4MB Cache, Retail
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=632054
GPU
1GB Palit/XVision 8500GT PCI-E(x16), Mem800MHz GDDR2, GPU450MHz, 16Streams, DSub, DL DVI-I
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=736203
Memory
2GB (2x1GB) Corsair TwinX XMS2, DDR2 PC2-6400 (800), 240 Pins, Non-ECC Unbuffered, CAS 5-5-5-12
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=255300
HDD
500GB Samsung HD502IJ Spinpoint F1, SATA II, 7200 rpm, 16MB Cache, 8.9 ms, NCQ
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=807030
I don't really have much to spend and just wanted to know is this decent for my price which is around £400
EVGA 123-YW-E175-A1, NF750i SLI, 775, PCI-E (x16), DDR2 1066/800, SATA II, SATA RAID, ATX
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=801000
CPU
Intel Core 2 Duo E6750, Conroe Core, S775, 2.66 GHz, 1333MHz FSB, 4MB Cache, Retail
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=632054
GPU
1GB Palit/XVision 8500GT PCI-E(x16), Mem800MHz GDDR2, GPU450MHz, 16Streams, DSub, DL DVI-I
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=736203
Memory
2GB (2x1GB) Corsair TwinX XMS2, DDR2 PC2-6400 (800), 240 Pins, Non-ECC Unbuffered, CAS 5-5-5-12
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=255300
HDD
500GB Samsung HD502IJ Spinpoint F1, SATA II, 7200 rpm, 16MB Cache, 8.9 ms, NCQ
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=807030
I don't really have much to spend and just wanted to know is this decent for my price which is around £400
A. YEAH, really good.
1GB video card will help in the future as programs and Games increase.
Don't forget to compare US sites as well to take advantage of the exchange rate which I think is $2 US to 1 UK Pound.
Shipping will be more, but you might save some.
Only suggestion to REALLY get this rig tricked out.. would be to add a 2nd Hard drive of the same capacity so you can Mirror the drives (RAID 0) for enhanced performance and data recovery.
Lastly, make sure your case has at least 1 120mm fan in it to help with airflow. -- I'd recommend a 450-500w powersupply if you don't plan on adding a 2nd Graphics card or over clocking it. 550-600w if you do plan on dual cards.
The PSU should have at least 1 120mm fan to keep things cool and quiet.
1GB video card will help in the future as programs and Games increase.
Don't forget to compare US sites as well to take advantage of the exchange rate which I think is $2 US to 1 UK Pound.
Shipping will be more, but you might save some.
Only suggestion to REALLY get this rig tricked out.. would be to add a 2nd Hard drive of the same capacity so you can Mirror the drives (RAID 0) for enhanced performance and data recovery.
Lastly, make sure your case has at least 1 120mm fan in it to help with airflow. -- I'd recommend a 450-500w powersupply if you don't plan on adding a 2nd Graphics card or over clocking it. 550-600w if you do plan on dual cards.
The PSU should have at least 1 120mm fan to keep things cool and quiet.
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