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Adding Hard Drives to RAID array.
I was looking this up in other areas within Netgear, but the best I got was general info, including the following, about what configuration X-RAID uses on installed drives: 1-2 HDD: RAID-1 (unpro...
SysEngJF wrote:
As far as auto-add and hot insert, I had read about that... though the docs I read seem a bit dated (they make it sound like it keeps the existing array, and I'd very much like to get it to RAID-6 once I hit that seventh drive). To add to the previous point, if the RN628X keeps the array as RAID-5 after the 7th disk is inserted (while online), then that would be a concern I'd need to know beforehand.
The data remains intact throughout the process, including the conversion to RAID-6 when the 7th disk is inserted.
SysEngJF wrote:
I heard of Red Plus, yet those seem rare compared to Red Pro.
Originally there was just Red and Red Pro.
But after the strong backlash when folks found out that WD had been rolling out SMR w/o telling folks, WD divided the Reds into a new Red Line (only SMR) and Red Plus (CMR). At this point there are a lot of WD Red Plus models - I haven't looked into availability. The current list is here: product-brief-western-digital-wd-red-plus-hdd.pdf
Thanks, StephenB . I did some research and it comes down to either WD Red Pro or WD Gold, though I lean a little more towards Gold due to the good experiences I've had with them, plus I've heard Red Pro can be loud to the point of causing some level of concern. I heard of Red Plus, yet those seem rare compared to Red Pro.
I thought of the re-sync each time a drive is added, which is why I'm thinking of starting at 3-6 drives to start it off, then add #7 and #8 one at a time.
As far as auto-add and hot insert, I had read about that... though the docs I read seem a bit dated (they make it sound like it keeps the existing array, and I'd very much like to get it to RAID-6 once I hit that seventh drive). To add to the previous point, if the RN628X keeps the array as RAID-5 after the 7th disk is inserted (while online), then that would be a concern I'd need to know beforehand.
The only real-time experience I've had with XRAID is my previous RN214, in which I used 4x Seagate ES.4 drives, all same size, speed, and firmware. The ReadyNAS made a RAID-5 out of them (via X-RAID) and it worked like a charm.
Just to be on the same page, yes. I have made 2 backups of all the data I plan to transfer to the new RN628X box.
SysEngJF wrote:
As far as auto-add and hot insert, I had read about that... though the docs I read seem a bit dated (they make it sound like it keeps the existing array, and I'd very much like to get it to RAID-6 once I hit that seventh drive). To add to the previous point, if the RN628X keeps the array as RAID-5 after the 7th disk is inserted (while online), then that would be a concern I'd need to know beforehand.
The data remains intact throughout the process, including the conversion to RAID-6 when the 7th disk is inserted.
SysEngJF wrote:
I heard of Red Plus, yet those seem rare compared to Red Pro.
Originally there was just Red and Red Pro.
But after the strong backlash when folks found out that WD had been rolling out SMR w/o telling folks, WD divided the Reds into a new Red Line (only SMR) and Red Plus (CMR). At this point there are a lot of WD Red Plus models - I haven't looked into availability. The current list is here: product-brief-western-digital-wd-red-plus-hdd.pdf
The OS actually converts the RAID type before it does the sync, as that's how MDADM works when changing the RAID type. It's all automatic and you have to turn XRAID off if you don't want that It converts a 2-drive RAID1 to a 3-drive RAID5 that is missing a drive (and thus has no redundancy), then it syncs the new drive to fill the gap. Likewise, it converts a 6-drive RAID5 to RAID6, then does the sync of the 7th. Though the interrim 6-drive RAID6 would seem like it should still have single redundancy, I'm not sure it does since the parity format is different for RAID6.
I found this from the developer of MDADM:
It is a very similar process that can now be used to convert a RAID5 to a RAID6. We first change the RAID5 to RAID6 with a non-standard layout that has the parity blocks distributed as normal, but the Q blocks all on the last device (a new device). So this is RAID6 using the RAID6 driver, but with a non-RAID6 layout. So we "simply" change the layout and the job is done
But he doesn't say if the "simple" process of changing the layout retains any redundancy as it does so.
You are actually best off starting with what space you think you will need for the immediate future (maybe a year), and adding drives as you need them. That allows you to space them out over more time, which can help in preventing nearly simultaneous drive failures due to equal age of the drives, will probably reduce your cost as drives get cheaper over time, and allows you to switch to a larger drive size for the added ones if you find your space requirements are growing faster than you originally thought.
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