RAID 10 for Data AND OS?

[commissarmo]

I'm wondering if my thinking is more relevant to HDDs than SSDs.

I have two RAID 10 arrays, both on hardware controllers, populated in SSD drives.

One is for data, with 4 SSDs, and the other is the system OS drive, also with 4 SSDs.

While the system RAID 10 is I think self explanatory (in terms of uptime, the system will not go down with a single drive failure),


** I'm not sure if the RAID 10 for DATA makes any sense? Access times will be better, but is it standard to put data only in RAID arrays as I've done?

Thanks in advance to any poster.

 

[GhislainG]

It isn't standard for home use, but if you can afford it, then it's an excellent configuration. I presume that you also perform regular backups?

 

[commissarmo]

Ok fair enough.

1) I was told that while RAID 10 makes sense for keeping a system operational (for 1 drive fail) it didn't make as much sense for data since, if a data drive fails, nothing goes offline per se... you just need to replace the disk, and write the backup files onto it.

I suppose though, the RAID array takes care of the issue where your last backup, however incremental, might not have caught the immediate file that was operational during disk fail, and presumably, it means the data stays constantly available while the array rebuilds.

2) I was also told that since SSDs "fail" a lot less than HDDs, that RAID 10 for SSDs was obsolete HDD thinking applied to SSD usage. Which I guess is true, since RAID is mainly used for HDDs, but presumably SSDs also have some kind of hardware fail rate? (and not merely a time-based performance degradation metric)?

3) and yes I'm paranoid about data loss since a cataclysmic crash some years ago. I use Acronis to image weekly, and then do incremental backup, with each RAID 10 set traced to another backup HDD. I also then copy the backup HDDs to an offsite personal server, put some key files in cloud storage, and have paper copies of text files in a safety deposit box.

 

[GhislainG]

I was also told that since SSDs "fail" a lot less than HDDs

This is not true. http://www.tomshardware.com/reviews/ssd-reliability-failure-rate,2923.html

 

[commissarmo]

A scintillating read. I was particularly interested in the suggestion that HDDs fail 'more gracefully' than SSDs, with some warning before their doom.

Now I'm wondering... if SSDs have the ability to fail abruptly... and given the RAID-array failure effect (a second drive failing during RAID rebuild) if perhaps HDDs are more secure in RAID since they can (maybe) survive just that extra bit of time to survive RAID rebuild, and allow a cold-swap of ALL new drives into the array.

 

[GhislainG]

Hard drives fail at rebuild time because they work harder, but that rarely occurs. Since they don't have moving parts, SSDs shouldn't have that issue.

 

[Hawkeye22]

Ok fair enough.

1) I was told that while RAID 10 makes sense for keeping a system operational (for 1 drive fail) it didn't make as much sense for data since, if a data drive fails, nothing goes offline per se... you just need to replace the disk, and write the backup files onto it.

All RAID will keep a system operational if there is a single drive failure. That is the whole purpose of RAID. RAID 0 isn't necessarily a true RAID since it's striping has no redundancy. You could have done a RAID 1 or RAID 5 using less drives.