Synology DS918+ - Disk/Volume Setup Query

cloud_dog

Hi

I've got a Netgear ReadyNas Duo V2 (RND2000 V2) with 2 x 2Tb drives (raid 1), and I am going to be 'treating' myself to a Synology DS918+.

The existing set up is primarily full of multi-media files with a small volume for home users to back-up to (local Word docs etc).

Initially, the Synology will be set up with 2 x 4Tb drives running raid1 and will be used for serving all the media files and running media services. The ReadyNas will be re-focussed to provide two distinct areas:

1. Back-up - Local PCs / phones / tablets etc files
2. Archive - For the above type data but no longer retained on the source device

The distinction is important because we have had an issue in the past where people's understanding of what it meant was different.

The question I have relates to the Synology and using the two remaining bays at some point in the future. As of today I am flexible in how this expansion might be used but I could envisage, for example, the 8 year old ReadyNas becoming 'tired' and possibly needing to be retired. I would then look to use the 2 x 2Tb ReadyNas drives in the spare slots of the Synology.

For info....NAS data is also backed up periodically on to external USB drives.

My question (finally)... Usually to add additional drives in to the Synology they need to be equal to or larger than the existing drives but, is there a way to configure the Synology to treat the two pairs of drives as two separate Raid 1 drive pairs? And would this allow for a smaller pair of drives to be utilised? For example Volume 1: HDD1 and HDD2, and Volume 2: HDD3 and HDD4?

that

I do not know about Synology, but no one else seems to be answering and I have a different issue for you with raid 1 & 5 and big data which time and size wise you may approach... and the answer is Raid 6.

In a perfect world, if one drive physically fails on your raid, you put in another disk and it is rebuilt. No problems.

In reality not everything always goes to plan. So if you have your raid 1. If one disk has data corruption, say your raid system always reads the good disk (remember raid is created on write, not on read) there is no fault, . Anyway good disk goes faulty, put in your new disk and that fault is duplicated and now you system is corrupt.

Same situation on raid 5 but at least three times the risk as there are a minimum of 3 disks and more chance of 1 in 3 going faulty, than one disk alone. One good disk has a hardware fault, on replacement, if another disk has a corruption, on rebuilding the raid the checksum and current data cannot be used calculate the missing data, rebuild and will fail.

Some people are talking about raid 7 not being good enough on very large data volumes. Raid 6 should suffice, but you do not want that one bit in 10^15 unrecoverable read error. It may never happen, but I have seen it on 300Gb raid systems many times, plus time and magnetic decay are not your friend. Better systems
like zfs refresh the blocks and do checksums to keep data valid.

I have picked 2 disk - 6TB each
ebuyer.com/760215-seagate-enterprise-capacity-6tb-3-5-hard-drive-512e-sata-st6000nm0115
ebuyer.com/737976-wd-gold-hard-drive-6tb-sata-6gb-s-wd6002fryz

A long warranty is nice, but reliability could be better purchase statistic
wd say 2.5 million hours MTB and seagate say 2,000,000 hours MTB
Both WD and seagate say Non-Recoverable Errors (same as unrecoverable read errors -URE ) 1 per 10^15. Go to a non enterprise drive and these numbers drop.

The Winner on paper is WD due to MTB, as they both have the same URE. A failed drive on raid is better that one with URE. I also did not check to load cycles.

The blue WD cheap 6TB drive ebuyer.com/719745-wd-blue-6tb-3-5-sata-desktop-hard-drive-wd60ezrz states that it has a ure of 1 per 10^14 and lower load/unload cycles

computerweekly.com/tip/Mean-time-between-failure-vs-load-unload-cycles

Did you hear the one about the guy who bough a drobo box which became faulty. It was replaced under warranty, just the new firmware did not recognise the old format of the drives and the data could not easily be gotten back, unless he bought an old drobo from ebay

Did you hear the one where a guy bought a ???? box, fitted 4 2TB Samsung drives. One drive became faulty,. the new samsung drive had different firmware and would not join the raid when inserted. Samsung would not take it back as there was nothing wrong with the drive and the ????box manufacturer said it is not their issue, because it is a drive issue and recreating the raid from new will work proving the ???? box is ok - catch22

John_Gray

cloud_dog wrote: »

... is there a way to configure the Synology to treat the two pairs of drives as two separate Raid 1 drive pairs?

I am tempted to think the answer is No, and you really need two NAS boxes to achieve that result.
By all means search the Synology documentation or contact their technical support, but I think you'll be disappointed.

RobTang

Yep Synology NAS does allow multiple volumes and their config can be entirely separate (ie different raid types and drive sizes)

chiny

Many years ago, I recall testing the Synology software before buying. Hmm, er, fidget... ah... this link looks the one but not tried for the OP question.