# Do web servers get bad sectors?

1. May 12, 2015

### Benjamin_harsh

Do web servers get bad sectors?
what i am asking is do physicsforums servers get bad sectors like our PC hard disk or not?
for suppose this forum thread got bad sectors, how does it open?

2. May 12, 2015

### Merlin3189

""Do web servers get bad sectors? "" - I don't know, but I would think it advisable to assume that they might. A program of preventive maintenance - eg. replacing drives well before their MTTF - might help lower the chances. I think it is possible to monitor the recording quality, so that blocks where retrieval confidence is falling can be taken out of use before they fail and drives with high levels of bad blocks can be replaced.

I would also expect that the web hosting service provider would mitigate their effects, should they occur.
The recording on the disc could incorporate redundancy to effect error detection and correction.
Redundant arrays of discs could cope with uncorrectable errors.
If, despite all precautions, live files were corrupted, I hope there would be a backup so that service could be resumed quickly. (Though this is really just another type of redundancy.)

A lot depends on Service Level Agreements. The more important data availability is, the more people will pay and the more you can spend on precautions. Probably nothing will keep the site up when the sun becomes a red giant, but until then I think it's just a question of .

3. May 12, 2015

### DaveC426913

Any webhost will have sufficient fail-over and backup systems, as Merlin itemizes, that data is very rarely lost.

If you are utilizing a webhost where a single HD failure can cause loss of service or loss of data, it's time to get a new webhost.

4. May 12, 2015

### phinds

Of course they do. Web servers are just hard drives* and as Dave pointed out, hard drives get errors. Serious web sites use RAID servers to cover for bad sectors and other disk errors.

* actually "web server" is hard drive plus server software (and usually a database), not JUST a hard drive.

5. May 12, 2015

### Staff: Mentor

The college where I work used to have a simple web server for faculty, staff and students' personal web pages. (I used to help run it.) Every few years we had a disk crash and had to replace the disk and restore everyone's data from a backup copy. But we didn't use anything fancy like a RAID for redundancy. If we had had a suitably configured RAID, when one of the disks failed, we could have simply swapped it out for a new one without affecting service.