Afrihost service - hosting complaint

ld13 said:
What do you feel is wrong with RAID 1?
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It's slightly better than RAID 5... At least with RAID1, if 1 drive fails you still have something left. With RAID5, if one drive dies you have nothing left - especially since RAID5 is only being setup with 3 drives....
Imagine the horror when that poor client finds out his precious RAID5 meant absolutely NOTHING in terms of protection... Many, many ISP's sell 3-drive RAID5 servers and think, "this is the bomb!"
 
With Raid 5 one drive can fail and the server will still be running and you can just replace the drive to rebuild the raid.
 
SoftDux-Rudi said:
It's slightly better than RAID 5... At least with RAID1, if 1 drive fails you still have something left. With RAID5, if one drive dies you have nothing left - especially since RAID5 is only being setup with 3 drives....
Imagine the horror when that poor client finds out his precious RAID5 meant absolutely NOTHING in terms of protection... Many, many ISP's sell 3-drive RAID5 servers and think, "this is the bomb!"
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Incorrect.

Anyway raid is not a backup. It's redundancy. A backup will allow you to recover a file that was deleted. Raid will not.
 
SoftDux-Rudi said:
Please, enlighten me.
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3 disk raid 5 has two data segments and one parity segment for each stripe, distributed among the disks. Loss of one disk allows on the fly but slower reading of data. The set can be reconstructed when the failed disk is replaced.
As for your 1tb comment - the size of the disk is irrelevant.
 
SoftDux-Rudi said:
Sure, but you need more than 3 drives...
And, if the drives are 1TB drives, you WILL loose your data.
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With Raid 5 you need a minimum of 3 drives and will lose 1 drive space for redundancy. If you use 3 x 1 TB drive in raid 5 you will have 2TB volume to save data, one drive can fail and you can still read the data on the volume.
 
Anyone running Raid 5 with 1TB drives might as well run Raid 0 because if a drive fails you are going to lose your data regardless.
This is because raid 5 (and raid 6) suffer from URE's (Unrecoverable Read Errors). When a drive fails in Raid 5, there is a % change that when trying to rebuild the failed drive, a URE will occur and there will be data loss.

This URE percentage goes up very quickly and with a very steep curve when your raid size goes above 1TB. Using 1TB in Raid 5 has some ridiculous stat like there is a 70% chance you will hit a URE and have data loss if a drive fails in Raid 5. This is partly why Raid 6 exists. It resets this percentage so that the 70% mark is up near the Petabytes.

You are better off running Raid 1 with 2x 2TB drives than you are running Raid 5 with 3x 1TB drives. At least in raid 1 your data is a lot more safe in the event of a single disk failure and your write speeds will be quicker.


Raid is not a backup solution and does not replace the need for proper backups.
Raid is a hardware redundancy technology.
 
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Murmaider said:
Anyone running Raid 5 with 1TB drives might as well run Raid 0 because i a drive failure you are going to lose your data regardless.
This is because raid 5 (and raid 6) suffer from URE's (Unrecoverable Read Errors). When a drive fails in Raid 5, there is a % change that when trying to rebuild the failed drive, a URE will occur and there will be data loss.

This URE percentage goes up very quickly and with a very steep curve when your raid size goes above 1TB. Using 1TB in Raid 5 has some ridiculous stat like there is a 70% chance you will hit a URE and have data loss if a drive fails in Raid 5. This is partly why Raid 6 exists. It resets this percentage so that the 70% mark is up near the Petabytes.

You are better off running Raid 1 with 2x 2TB drives than you are running Raid 5 with 3x 1TB drives. At least in raid 1 your data is a lot more safe in the event of a single disk failure and your write speeds will be quicker.
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You're saying that a 3 disk raid 5 array can't survive two disk failures. You're absolutely right.
 
Sinbad said:
You're saying that a 3 disk raid 5 array can't survive two disk failures. You're absolutely right.
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No, I'm saying that if you have a single disk failure in a Raid 5 volume that is above 1TB in size, there is an extremely high chance that you will have data loss.
 
Murmaider said:
No, I'm saying that if you have a single disk failure in a Raid 5 volume that is above 1TB in size, there is an extremely high chance that you will have data loss.
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You're implying that any disk above 1TB in size has an extremely high chance of having unrecoverable read errors?
 
Sinbad said:
You're implying that any disk above 1TB in size has an extremely high chance of having unrecoverable read errors?
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This will explain it a bit better than I can http://www.zdnet.com/blog/storage/why-raid-5-stops-working-in-2009/162 http://forums.storagereview.com/index.php/topic/34094-is-raid-56-dead-due-to-large-drive-capacities/

I see the percentage I mention is a bit off but I can confirm that so far we have hit a URE 100% of the time during a rebuild in Raid 5. This is why we only use Raid 1 and Raid 10 now.

Besides that, I am still unsure why anyone would want to use raid 5 now days with the overhead and potential issues, its just now worth it.
 
Murmaider said:
This will explain it a bit better than I can http://www.zdnet.com/blog/storage/why-raid-5-stops-working-in-2009/162 http://forums.storagereview.com/index.php/topic/34094-is-raid-56-dead-due-to-large-drive-capacities/

I see the percentage I mention is a bit off but I can confirm that so far we have hit a URE 100% of the time during a rebuild in Raid 5. This is why we only use Raid 1 and Raid 10 now.

Besides that, I am still unsure why anyone would want to use raid 5 now days with the overhead and potential issues, its just now worth it.
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OK let me paint a scenario:
Raid 1, 2x1TB disks

Disk 1 fails. You replace it.
During the mirror rebuild, disk 0 has an URE.

Surely you're just as fscked?
 
What you say applies, to people using PC based SATA RAID arrays.

I work for a large multinational. We STILL have more than 50% of our servers on ADAPTEC raid 5 with SCSI. Having worked for RAID 5 SCSI products fro more than 15 years. I have to say that there is a failure rate.

But on enterprise products. This is easily mitigated. Most of our server have RAID cards with memory backup.

The beauty these days is the Software interface notifies the syadm before there is a failure and we hot swap the drive. ALL of our servers has at least one Hard drive sitting as HOT Spare drive.

The usage of SATA drives for data redundancy is flawed because of the error rates of these drive increase when you pass a certain percentage of mechanical usage in a time frame.

Just to clear, this occurs on both SCSI drives and SATA raid arrays. But with enterprise scsi raid products , you are able to mitigate the errors leading to total loss of data.
 
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Sinbad said:
OK let me paint a scenario:
Raid 1, 2x1TB disks

Disk 1 fails. You replace it.
During the mirror rebuild, disk 0 has an URE.

Surely you're just as fscked?
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No. With RAID 1, DATA is mirrored on both drives. you have two identical copies.

If one drive fails you still have 100 percent of the data on the other drive.

A raid 1 array rebuild is different to a raid 5 array rebuild.
 
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Just to clear up confusion here - it looks like we had actually mis-labelled the product page - so thanks to everyone for bringing this issue up.

RAID has nothing to do with backups - as we don't actually offer backups as a general service. We do offer Free backup space (via FTP) on a backup server, but that is not something we perform - it's up to the client. The RAID label actually refers to RAID level (1 or 5) and not to anything related to backups.

We can offer R1Soft as a solution on request, which you can discuss with your account manager if you're looking for a solution like this.

Hope that helps clear up the confusion.
 
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silver6933 said:
No. With RAID 1, DATA is mirrored on both drives. you have two identical copies(excluding timestamped updates).

If one drive fails you still have 100 percent of the data on the other drive.

A raid 1 array rebuild is different to a raid 5 array rebuild.
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An unrecoverable error on a mirror rebuild will be as bad as an unrecoverable error on a raid5 build. Every bit on the disk needs to be read in both cases.
 
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