Add disks but keep performance?

[helloha]

Hi,

Below is my HD config of my fileserver. I chose 2 vdefs of 5 disks in raid z1 because the performance should be best in that setup.

But now I need more space but I don't have the budget to put another set of 5 disks. Can I add another vdef in raidz1 of 3 disks and keep my performance? or will performance of the overall setup go down?

Also can I add more disks to the VDEF of 3 disks to make it into another set of 5 disks in the future? (and keep the data)

Thanks for any advice,
K.

Code: Select all

	NAME        STATE     READ WRITE CKSUM
	TSW-POOL    ONLINE       0     0     0
	  raidz1-0  ONLINE       0     0     0
	    da0     ONLINE       0     0     0
	    da1     ONLINE       0     0     0
	    da2     ONLINE       0     0     0
	    da3     ONLINE       0     0     0
	    ada0    ONLINE       0     0     0
	  raidz1-1  ONLINE       0     0     0
	    da4     ONLINE       0     0     0
	    da5     ONLINE       0     0     0
	    da6     ONLINE       0     0     0
	    da7     ONLINE       0     0     0
	    ada1    ONLINE       0     0     0
	cache
	  ada2      ONLINE       0     0     0

[ChriZathens]

I believe performance won't be affected. The best practice is to add vdevs of same type, which is what you are after..

BUT
If you add a 3disk raidz you won't be able to add later another 2 disks at that vdev. You will have to create a new vdev. Keep in mind that once a vdev is added in a pool it cannot be removed.
This means that once you add a 3 disk vdev in the pool, not only you can't add more disks to it, but also you can't destroy the vdev and create it again with 5 disks.
I am afraid you will have to pay for two extra disks. A workaround would be to create a separate pool with the existing disks and once the budget allows you to purchase two more, backup whatever data have been copied to this pool, destroy the pool and use existing + new disks to create a new vdev which then can be added to the existing pool of two raidzs
Another workaround would be what I had once done:
I needed to create a NAS for a friend. The case could fit 5 disks, but he had only purchased 4. He had no budget left for the 5th. He had paid for the NAS and the disks (3TB disks - two years ago - they were very expensive back then). Since he did not want to wait another 1-2 months to get the 5th, we created a 5disk raidz with those 4x3TB + 1x1TB that we had laying around. That way, the created pool, instead of ~12TB Raw space ended up with ~4TB Raw space (5x1TB minus 1TB for parity). He started adding data and once he purchased the 5th 3TB disk we replaced the 1TB hdd and expanded the space. Perhaps you can follow the same approach with two smaller existing disks, until you purchase 2 more

[crowi]

Also can I add more disks to the VDEF of 3 disks to make it into another set of 5 disks in the future? (and keep the data)

No, this is not possible.

You can add a vDev of three disks without loosing performance:
"RAIDZ1 vdevs should have 3, 5, or 9 devices in each vdev"

How do you backup your big pool?

[helloha]

Thanks for the quick reply!

Perhaps adding a separate pool with 3 disks is the best option then.

How do you backup your big pool?

A very tedious manual process involving 6 G-Raid disks. But it is an offsite backup so there is really no other way.

[simonlebon]

You can add a vDev of three disks without loosing performance:
"RAIDZ1 vdevs should have 3, 5, or 9 devices in each vdev"

Ok, I need some advise and didn't want to start a new topic because the questions I have are related to this topic.

The maximum # of disks my case and mobo can host is 14, (6 * 3.5 inch and 8 * 2.5 inch, see the hardware specs below).
Main purpose is to store and stream movies, CCTV recordings (D1) and music. So transfers of singular, rather large files are most common. Therefor, I would like that the continues sequential write performance is high.

I want to start with 6 disks that I have laying around.
-Should I create 3 striped mirrors (2 disk per Vdevs) in a pool or 2 striped RaidZ1 (3 disk per Vdev)?

-What are the best options for expanding in the future? Add a striped mirror or RaidZ1 vdev to the pool? (besides replacing disks in a Vdev of course)

I tend to lean towards striped mirrored but I don't know if the throughput will be as high as (striped) RaidZ1 would be.
-I.o.w. what is the relation between striping and (sequential) throughput?

Currently I have a NAS4FREE server running based on an AMD X2 5050E, 4 disk RaidZ1 (<--yeah, I know) which performs great but needs to be replaced because its upgrade capability limit is reached. Besdides that, it is running since 2008.

The hardware that will replace this server;
SuperMicro X10SL7-F (flashed to IT), Pentium G3420, 32GB ECC DDR3-1600, Seasonic S12G 550W PSU, IPC E420 case with 2 * Icydock MB994SP-4SB-1.
Will be running on bare metal.