SAN - Nearline SAS only?

[Tall_Paul]

Hi all

 

I am in the process of getting quotes and recommendations for a new SAN.

 

I have five servers that I am going to virtualise (two DC's, two DB servers and a mail security server). I'll also be adding new servers that don't currently exist (for example, we have a NAS rather than a file server).

 

Quick question though. When I've bought SANs in the past it has been tiered storage. A mix of SAS (for OS', databases, etc) and nearline SAS (for file storage, etc).

 

I've ran the Dell DPACK utility on my current servers and, as a result of this, one of the consultants has recommended a SAN containing only nearline SAS disks.

 

Now, I know this keeps the costs down but I do find it odd to have no SAS disks at all. Has anybody else got anything similar to this?

Edited July 7, 2015 by Tall_Paul

[Steve21]

We ran NL-SAS on backup SAN before, but never on main as obviously worse speed/reliability. Wouldn't like to run your production on 7.2k disks?

 

Guess it's a bit different if you are tiering as you said, but certainly wouldn't go for full NL-SAS

 

Out of curiosity was the consultant for a reseller or direct company?

 

Steve

[teejay]

I think Dell must have a load of nearline SAS disks stuck in their warehouse, we were quoted all nearline as well.

It seems like Dell are in one of those useless phases at the moment, which is a shame as I like their kit but they just don't seem to be offering sensible configs.

[Tall_Paul]

We ran NL-SAS on backup SAN before, but never on main as obviously worse speed/reliability. Wouldn't like to run your production on 7.2k disks?

 

Guess it's a bit different if you are tiering as you said, but certainly wouldn't go for full NL-SAS

 

Out of curiosity was the consultant for a reseller or direct company?

 

Steve

 

The consultant was for a reseller who I have used a lot at my last school.

 

I can't get my head around all nearline SAS either. I've bought two SANs in the past and neither of them had this configuration!

 

I've popped them an email this morning asking them to explain it. If I implement something like this and it's crap it'll be my bottom that's on the line!

[Steve21]

Might want to ask them to see the DPACK report, as should show you all the graphs etc and statistics of the server. Bearing in mind even "if" it looks ok for that server, if you're putting more onto it + HOST overlay etc, it could still need more, but guess it depends how close you are to it

 

E.g. Your NAS isn't going to show up anything on the DPACK so if that's your main fileserver it's kind of irrelevant the details of the DPACK.

 

Steve

[Tall_Paul]

Might want to ask them to see the DPACK report, as should show you all the graphs etc and statistics of the server. Bearing in mind even "if" it looks ok for that server, if you're putting more onto it + HOST overlay etc, it could still need more, but guess it depends how close you are to it

 

E.g. Your NAS isn't going to show up anything on the DPACK so if that's your main fileserver it's kind of irrelevant the details of the DPACK.

 

Steve

 

I'm going to ask them to explain the results of the DPACK report to me. I only ran it for 24 hours so it might be worth running it for longer.

 

I couldn't run DPACK on the NAS even if I wanted to! However, I'm not concerned about that (happy to put files onto nearline SAS).

 

It may be that nearline SAS will be fine. But none of my physical boxes contain disks of that spec, they are all either 10 or 15K SAS disks!

 

Hence I am somewhat bemused!

[Geoff]

A Nearline Storage SAN would only make sense for Archive/Backup or if you are going to use a tiered storage solution. Based on your workloads it sounds like you would want a 'normal' disk SAN with Flash cache (or tiered Flash/Disk).

[Tall_Paul]

A Nearline Storage SAN would only make sense for Archive/Backup or if you are going to use a tiered storage solution. Based on your workloads it sounds like you would want a 'normal' disk SAN with Flash cache (or tiered Flash/Disk).

 

Yes, I thought something like this too (though maybe tiered with SAS storage and nearline SAS).

 

All nearline SAS (presumably spinning at 7200RPM) makes no sense to me at all. Unless there's been some sort of fundamental change in nearline SAS disks I can't understand they any consultant would recommend a production SAN containing only those disks.

[PotNoodleTech]

It sounds like you have enough experience to drop kick the "consultant" and just ask them to supply a specific config.

 

Use SAS for production workloads - you got that right

Use SSD Cache if your SAN supports it - you got that right.

 

All you really need to do is pick the number of disks you want and order it?

[Norphy]

We are running one of our virtual farms on a SAN with 7200rpm near line SAS Drives and have been for a good four years. It's been running database servers and email servers. It has 14 disks in RAID50 and we have had no complaints about its performance.

 

At this stage in its life, the drives have an annoying habit of failing when compared to our SANs running full SAS drives but this is why you run the drives in RAID and have cover for them

[Tall_Paul]

We are running one of our virtual farms on a SAN with 7200rpm near line SAS Drives and have been for a good four years. It's been running database servers and email servers. It has 14 disks in RAID50 and we have had no complaints about its performance.

 

At this stage in its life, the drives have an annoying habit of failing when compared to our SANs running full SAS drives but this is why you run the drives in RAID and have cover for them

 

That's interesting, thanks for that.

 

The consultant has told me that DPACK reported 1,168 IOPS on the 95th percentile and peaking to 1,700 IOPS on the 99th percentile.

 

Apparently the SAN they have recommended is capable of just over 5000 IOPS which is why they've recommended it.

[Steve21]

How much are you paying for that SAN? We don't get near 5k on ours.

 

I mean a 10K SAS is maximum what 150~ IOPS, so even 24 would only be 3.6k without taking hotspares etc into account

 

Steve

[Steve21]

Just checked on ours. 24 disks at 10K

 

Gives us 1146 IOPS (RAID 6), if we used RAID 10 would be 2919

 

So again going to depend what you're configuring yours as, as even 24x 10K SAS would be struggling if you're RAID6

 

Steve

[pantscat]

Depends on the SAN and how the file system works - Nimble use NL-SAS with a flash cache and the IOPS are amazing.

I'd really recommend looking at these.

[Tall_Paul]

The SAN they have quoted us for is a Dell Equalogic PS4100 containing 12TB of Nearline SAS disks configured as RAID 10.

 

It's about £7.5K.

[Steve21]

I don't think you'll get anywhere near those figures unless I'm missing something. I'm assuming that's only 12 disks then too? 12x 1TB?

 

Even our 10K SAS doesn't get that IOPS in RAID10 config (and what 7.2K is roughly 2/3 IOPS?):

 

This is our PS4100 with 24x 10K SAS:

 

 

 

Steve

[bossman]

@Tall_Paul

 

Have you looked into Synology

 

We have found them an excellent product and currently running 7 VMs in total on it, we are shortly going to be running 2 x RS3614xs in sync with 12 1TB SSDs in each for our backend Hyper-V platform and the current one we have will be coupled with another with 8TB drives for 96TB formatted storage so when added we will have 128TB of pure storage for both backups (VEEAM) and staff and student data storage.

 

Excellent pricing too! Interface is so good and they come with 5 years warranty also, what more can I say for around £4k - £5k

Edited July 7, 2015 by bossman

[Tall_Paul]

I don't think you'll get anywhere near those figures unless I'm missing something. I'm assuming that's only 12 disks then too? 12x 1TB?

 

Even our 10K SAS doesn't get that IOPS in RAID10 config (and what 7.2K is roughly 2/3 IOPS?):

 

This is our PS4100 with 24x 10K SAS:

[ATTACH=CONFIG]31452[/ATTACH]

 

 

 

Steve

 

That is really, really useful. Many thanks for that.

 

- - - Updated - - -

 

@Tall_Paul

 

Have you looked into Synology

 

We have found them an excellent product and currently running 7 VMs in total on it, we are shortly going to be running 2 x RS3614xs in sync with 12 1TB SSDs in each for our backend Hyper-V platform and the current one we have will be coupled with another with 8TB drives for 96TB formatted storage so when added we will have 128TB of pure storage for both backups (VEEAM) and staff and student data storage.

 

Excellent pricing too! Interface is so good and they come with 5 years warranty also, what more can I say for around £4k - £5k

 

No, I haven't looked at Synology yet. I may well do though!

[bossman]

@Tall_Paul

 

Forgot to mention that our current synology box (36TB RAID 6) has just 12 SATA 5400 4TB WD Reds and supports 7 VM's plus their Virtual disk storage too!

 

The newer version supports 8TB SATA 7200rpm and also 1TB SSD's in a mix

 

So easy to setup with the cool interface

[Geoff]

My Ceph Cluster tops out at 114k IOPS. But it is tiered. If I turn off the tiering I get 9k IOPS off the Nearline SAS drives in it, I suspect that's the memory caching throwing the numbers out though.