I have a 516 loaded with 4TB drives using X-RAID (or what I assume is actually X-RAID2) on latest OS6. Assuming I understand it correctly if I want to expand my memory space I have 3 options.
Replace the NAS with new one or get a second NAS.
Replace some drives (one at a time).
Add and expansion box using the eSATA Port
Some questions realted to 2 & 3.
Related to #2) For example, if I swap out 3 of the 4TB for 8TB I should get a second expansion with the extra space. If I understand things correctly, my original space would be the same (4TB x 5 + parity) but I would add a second (8TB + parity) expansion? Does this show as a seperate storage volume or just expand the exisiting one?
Related to #3) I have an option to get a EDA500-100NAS from someone. If I add an this expansion eSATA box with 3 x 4 TB drives I assue it just keeps expanding my volume so now I would be (4TB x 5 + parity). Is this correct?
If I add the expansion eSATA box with 3 x 8 TB drives I assue it just keeps expanding my volume so now I would be (4TB x 5 + parity plus 8TB x 2 + parity). Is this correct?
When adding the expansion eSATA does this show as a seperate storage volume or just expand the exisiting one?
I am open to feedback on questions and ideas (pro/cons) of the 3 expansion options. I am assuming Option #1 is most expensive but most flexible while option #3 is least expensive but least flexible.
Related to #2) For example, if I swap out 3 of the 4TB for 8TB I should get a second expansion with the extra space. If I understand things correctly, my original space would be the same (4TB x 5 + parity) but I would add a second (8TB + parity) expansion? Does this show as a seperate storage volume or just expand the exisiting one?
3x8TB+3x4TB would give you a one 28 TB volume (~25.4 TiB). The capacity rule generally is "sum the disks and subtract the largest". (This rule applies if you replace disks with ones that are at least as large as the biggest drive in the array).
Technically this would be done by creating a second RAID group - which in this hypothetical would be 3x4 TB RAID-5 (using the extra 4 TB of space on the three 8 TB disks). This is concatenated with your existing 6x4TB RAID group, so it is invisible to you.
@Retired_Member wrote:
If I add the expansion eSATA box with 3 x 8 TB drives I assue it just keeps expanding my volume so now I would be (4TB x 5 + parity plus 8TB x 2 + parity). Is this correct?
First, I wouldn't recommend the EDA500. People here have had issues with it - particularly slow sync times. If you did go this route, you would have a different volume on the EDA500. Your main volume on the RN516 would be 20 TB; the EDA500 volume would be 16 TB.
@Retired_Member wrote:
I am open to feedback on questions and ideas (pro/cons) of the 3 expansion options.
Given that you can already get 16 TB drives, I think it makes more sense to just upgrade the drives to bigger ones as you need more space.
Though backup is another consideration, as RAID isn't enough to keep your data safe. Getting a second NAS for backup is something you should consider.
But as far as pricing goes, a new NAS is certainly the most expensive. The EDA500 was discontinued quite a while ago, so if you went that route you'd either need to get something used or pay an exhorbitant price.
Thanks for the feedback. I did the math wrong (it was supposed to be 4TB x 3 and 8TB x 3) but your explianation cleared it up for me. I was overthinking the math. Also thanks for the feedback on the EDA500, I am going to skip going that route.
I have a second off-site ReadyNAS 2-drive (RN422) for the important stuff in JOBD with 2 x 10TB and do RSYNC on them on a schedule so this would just be to expand for other usage. I have a friend who likes his Synology and I was looking at the RN626 and RN628 but I don't think I need 3 NAS systems.
I had a 516 with one real EDA500 and another brand of eSATA expansion chassis that the NAS recognized as an EDA500 and ultimately went another direction. The eSATA plug on one got accidently disconnected one time while the unit was on, and the volume became read-only due to BTRFS errors. The only solution was to re-create it and restore data. As @StephenB said, sync and scrub times were abominably slow, and I only had 3TB drives in one and 4TB in the other. When those processes were ongoing, it slowed other processes on the NAS and reading/writing that volume was extremely slow and unreliable. Splitting a single 3Gbps channel between 5 drives is just a bad concept for RAID.
If one used it exclusively for a bunch of separate JBOD volumes, or only for archival data rarely accessed, maybe it could work. But as a working RAID volume, it was simply not working.
