RAID Question

[HawkJ]

Hi. I am new to RAID. And would like to deploy it in an enterprise grade environment. We are planning on deploying freenas as the main storage. But to protect against data and user data loss, I am thinking of using raid for backup. Can raid 1 be used for freenas? And is it capable of instantly pointing the data (without restarting the server) to the second hard drive when the first hard drive fails?

 

Any help is appreciated. Thanks. 

[Oshino Shinobu]

FreeNAS supports pretty much every type of RAID, as most of it is done through software, rather than hardware RAID. 

 

For enterprise grade, RAID 1 is often wasteful and doesn't scale, so you're pretty limited. However, if you're only using two drives, RAID 1 will do just fine. If a drive fails, there should be no significant interruption in the service (there may be some if a drive fails mid-transfer). 

 

EDIT: Also, to be clear. RAID is not a backup, it only provides redundancy. A backup should ideally be separate from the main storage, with off-site copies if the data is very important. 

[Quindor]

Wow, looking to deploy in an "Enterprise grade environment" without good preparation can become a disaster! Also, Freenas and a RAID1 is nowhere near Enterprise grade.

 

• What kind of volume (TB's) are you looking at?
• How many IO (Throughput/latency) are you looking at?
•    (How many users, what are they going to do, only CIFS shares or also NFS and/or iSCSI?, VMware/Virtualization running from it or using it's storage?)

 

As @Oshino Shinobu explained above, RAID1 (mirror) will protect you against hardware (disk drive) failure but nothing other then that. A backup is something different and you need to have it aside from having RAID1.

 

Also, RAID1 is 2 disks only and thus because of that automatically low performance. If you need higher performance you will need to look at either RAID10 (multiple striped mirrors) or RAID5/6, etc.. Each comes with it's own pros and cons, especially when using ZFS (which Freenas does in the background).

 

Could you explain your intended setup and use case a bit better? Then we might also be able to give you better advice.

[Eniqmatic]

9 minutes ago, Quindor said:

Wow, looking to deploy in an "Enterprise grade environment" without good preparation can become a disaster! Also, Freenas and a RAID1 is nowhere near Enterprise grade.

 

• What kind of volume (TB's) are you looking at?
• How many IO (Throughput/latency) are you looking at?
•    (How many users, what are they going to do, only CIFS shares or also NFS and/or iSCSI?, VMware/Virtualization running from it or using it's storage?)

 

As @Oshino Shinobu explained above, RAID1 (mirror) will protect you against hardware (disk drive) failure but nothing other then that. A backup is something different and you need to have it aside from having RAID1.

 

Also, RAID1 is 2 disks only and thus because of that automatically low performance. If you need higher performance you will need to look at either RAID10 (multiple striped mirrors) or RAID5/6, etc.. Each comes with it's own pros and cons, especially when using ZFS (which Freenas does in the background).

 

Could you explain your intended setup and use case a bit better? Then we might also be able to give you better advice.

I'm going to have to slightly disagree with your statement of FreeNAS not being "enterprise grade". Given that TrueNAS is designed for the enterprise, and FreeNAS is *almost* exactly the same software, I think that is a bit of a harsh assessment. And judging by your answer, you don't need me to tell you how "enterprise" ZFS is. 

 

I know you will say that FreeNAS is not TrueNAS, but the underlying technology is essentially the same, so I wouldn't go as far as to say that.

 

Just my opinion however!

[Quindor]

1 minute ago, Eniqmatic said:

I'm going to have to slightly disagree with your statement of FreeNAS not being "enterprise grade". Given that TrueNAS is designed for the enterprise, and FreeNAS is *almost* exactly the same software, I think that is a bit of a harsh assessment. And judging by your answer, you don't need me to tell you how "enterprise" ZFS is. 

 

I know you will say that FreeNAS is not TrueNAS, but the underlying technology is essentially the same, so I wouldn't go as far as to say that.

 

Just my opinion however!

Ho, hold up!

 

I didn't mean that using FreeNAS immediately disqualified the whole setup. I just meant that slapping some hardware together and putting FreeNAS on it with two drives in a Mirror isn't Enterprise grade! I could have written that better though, my bad.

 

As long as you have decent knowledge of the underlying Hardware, ZFS, etc. I see no problems running ZFS (or FreeNAS in that sense) as an Enterprise level platform. I know several companies who run whole racks full of ZFS storage (most on Nexenta, but still).

 

So I think we can agree just fine here.

[Eniqmatic]

1 minute ago, Quindor said:

Ho, hold up!

 

I didn't mean that using FreeNAS immediately disqualified the whole setup. I just meant that slapping some hardware together and putting FreeNAS on it with two drives in a Mirror isn't Enterprise grade! I could have written that better though, my bad.

 

As long as you have decent knowledge of the underlying Hardware, ZFS, etc. I see no problems running ZFS (or FreeNAS in that sense) as an Enterprise level platform. I know several companies who run whole racks full of ZFS storage (most on Nexenta, but still).

 

So I think we can agree just fine here.

Ah, just the wording confused matters then!

 

Agreed, RAID1 is just a no. No excuse for it to be used anywhere these days!

 

OP, Add a "Z" and +1 your number to the above then we will talk 

[Oshino Shinobu]

31 minutes ago, Quindor said:

Also, RAID1 is 2 disks only and thus because of that automatically low performance

RAID 1 can be more than two drives. It's simple mirroring, so can theoretically be used with an unlimited amount of drives, all mirrors of the "master" drive. Needless to say, more than 2 drives is wasteful and RAID 5 and 6 should be considered if looking at more drives. 

 

RAID 1 can also be used to increase read performance by using striped reading, similar to how reading on RAID 0 works. That being said, the support for striped reading is not exactly common. I don't think FreeNAS supports it, so it's kind of out of the picture anyway. 

[Quindor]

43 minutes ago, Eniqmatic said:

Ah, just the wording confused matters then!

 

Agreed, RAID1 is just a no. No excuse for it to be used anywhere these days!

 

OP, Add a "Z" and +1 your number to the above then we will talk 

Well, actually using Mirrors with ZFS is very much recommended, just not one of them.

 

RAIDz1/z2 is NOT RAID5/6! Always remember that! Yes they share that z1 uses 1 parity stripe and z2 uses 2 party stripes, but that's it. Where RAID5/6 has a fixed stripe size RAIDz1/z2 does not. And because of this random I/O performance of a RAIDz1/z2 will always be the same performance as a single disk in the array, where with RAID5/6 it can scale depending on I/O pattern and stripe size. Using multiple mirrors (or RAIDz1/z2's) in a single pool is the only way to raise I/O performance with ZFS (besides caching SSD/Flash (ZIL, L2ARC).

 

Because of this any larger install which are running services (Real big file server, iSCSI/NFS for VMware, etc.) from their ZFS volumes should look at running multiple SAS cabinets and running the RAID1s split between two external cabinets so that if a whole cabinet fails (power supply, cabling, etc.) it still wouldn't pull down your whole environment. And sizing that setup with multiple cabinets the more storage you need.

 

In an Enterprise environment RAIDz1/z2 is only suitable for large data retention, in my opinion. But remember, in a real enterprise environment! I use a RAIDz1 at home and with plenty of caching this can work just fine for running some VM's, etc. 

[HawkJ]

@Oshino Shinobu @Quindor @Eniqmatic. Hey. Sorry guys. I didn't explain it well. So this is what is going on. We need a main file server with samba access for around 50 to 70 users. Raid 1 was just an example. I am not sure which raid to use for this situation. The storage will be around 6 to 8 TB. I want the primary server to have multiple redundancy (User data and data). I will also be setting up another local and a remote freenas server for backup. 

 

What i also wanted to know is if raid is configured for redundancy, will raid take care of automatically redirecting the users from the failed drive to a working drive(While the system is running)? Or do we have to restart the system in order for the redirection of data to work?

[Quindor]

57 minutes ago, HawkJizbel said:

@Oshino Shinobu @Quindor @Eniqmatic. Hey. Sorry guys. I didn't explain it well. So this is what is going on. We need a main file server with samba access for around 50 to 70 users. Raid 1 was just an example. I am not sure which raid to use for this situation. The storage will be around 6 to 8 TB. I want the primary server to have multiple redundancy (User data and data). I will also be setting up another local and a remote freenas server for backup. 

 

What i also wanted to know is if raid is configured for redundancy, will raid take care of automatically redirecting the users from the failed drive to a working drive(While the system is running)? Or do we have to restart the system in order for the redirection of data to work?

 

Ah yes, that explains a lot more.

 

When using RAID, all the disks that are part of the RAID sort of become one. After that 1 (or more depending on type of RAID level) disks can fail and the volume as a whole (the RAID) will remain active like nothing happened. You replace the disk, it rebuilds (or resilvers in the case of ZFS) and you are back to your original redundancy! From a usage standpoint, you don't notice anything, at most you will take a temporary performance hit (With RAIDz1/z2, with mirrors only during resilvering).

 

When looking to build something for 50 to 70 users you need to take a lot of things into account. For instance, is 1Gbps enough? It will depend on what they will do with it. Word/Excel usage, sure, no problem. But if they are working with bigger image or video files sometimes, you need to start thinking about 10Gbps connections (for the server).

 

Then also the hardware becomes more important. For that amount of users you either need a bunch of 7200rpm disks and a decent cache or you need to think about 10K/15K disks (although I would just skip those now-a-days and directly go to SSD's). It all depends on budget. As a general rule of thumb, think about having 10% of your total volume size in SSD cache size when using cheaper 7200rpm disks.

 

Also, depending on chassis, it's better (when using RAID1/mirrors) to have 16x1TB (8TB effectively) then 4x4TB (8TB effectively). Although you would have the same amount of space, 16x1TB will give you much more I/O then 4x4TB would. Cache and such is great but it can never make up for actual disk I/O in the end.

 

What kind of hardware are you looking at and what is your budget? For this, something like a SuperMicro server would be perfectly suited. They also have the correct type of LSI HBA's, etc.

 

For ZFS CPU is somewhat important (Again depending on RAID level, compression (LZ4 highly recommended!, deduplication (NOT recommended), etc.) but memory is the most important (get lots of it!). A remote box to do replication is a great idea, that one can be a bit less in specifications.

[leadeater]

I really wish ZFS didn't use RAID anywhere in their terminology, like Storage Spaces did with 2-Way Mirror/3-Way Mirror/Single Parity/Dual Parity etc, since RAID and ZFS are not alike at the technical level. I personally feel using RAIDZ-* etc was a mistake and just confuses matters.

 

There should be a rule on this forum, if you mean or are talking about ZFS then say ZFS and not RAID. Just a personal peeve as you can tell .

 

RAID is RAID, ZFS is ZFS, BTRFS is BTRFS etc the difference matters.

[HawkJ]

On September 2, 2016 at 5:15 PM, Quindor said:

Ah yes, that explains a lot more.

 

When using RAID, all the disks that are part of the RAID sort of become one. After that 1 (or more depending on type of RAID level) disks can fail and the volume as a whole (the RAID) will remain active like nothing happened. You replace the disk, it rebuilds (or resilvers in the case of ZFS) and you are back to your original redundancy! From a usage standpoint, you don't notice anything, at most you will take a temporary performance hit (With RAIDz1/z2, with mirrors only during resilvering).

 

When looking to build something for 50 to 70 users you need to take a lot of things into account. For instance, is 1Gbps enough? It will depend on what they will do with it. Word/Excel usage, sure, no problem. But if they are working with bigger image or video files sometimes, you need to start thinking about 10Gbps connections (for the server).

 

Then also the hardware becomes more important. For that amount of users you either need a bunch of 7200rpm disks and a decent cache or you need to think about 10K/15K disks (although I would just skip those now-a-days and directly go to SSD's). It all depends on budget. As a general rule of thumb, think about having 10% of your total volume size in SSD cache size when using cheaper 7200rpm disks.

 

Also, depending on chassis, it's better (when using RAID1/mirrors) to have 16x1TB (8TB effectively) then 4x4TB (8TB effectively). Although you would have the same amount of space, 16x1TB will give you much more I/O then 4x4TB would. Cache and such is great but it can never make up for actual disk I/O in the end.

 

What kind of hardware are you looking at and what is your budget? For this, something like a SuperMicro server would be perfectly suited. They also have the correct type of LSI HBA's, etc.

 

For ZFS CPU is somewhat important (Again depending on RAID level, compression (LZ4 highly recommended!, deduplication (NOT recommended), etc.) but memory is the most important (get lots of it!). A remote box to do replication is a great idea, that one can be a bit less in specifications.

Thanks a lot for that very informative reply. Helped me solve all the questions I had on it.