SAS 7.2K vs 10K

[Yaayuh!]

Hi All,
Basically speccing up some storage (file server) and looking at the following disk options for RAID 6:

8x 2TB 7.2K SAS
vs
8x 1.8TB 10K SAS

I'm a little torn as the 10K will give better performance but slightly less storage and at a higher cost.

My question is really what real-world difference will there be, it's not going to be for a high IOPS VM box, but just a file server.

TIA

 

[Wilderbeast]

I'd say you are very unlikely to notice any difference in a file server, in fact, I'd be tempted to drop SAS and get the cheaper SATA drives for a fileserver. What controller are you using?

 

[Yaayuh!]

I'd say you are very unlikely to notice any difference in a file server, in fact, I'd be tempted to drop SAS and get the cheaper SATA drives for a fileserver. What controller are you using?

That's what I was thinking.
It'll be a Dell Perc with 2GB NVRAM (H730P).
It'll be SAS regardless for its implementation, I won't drop to SATA.

 

[Armageus]

I'd agree with sticking with SAS, even though in theory there should be no differences, on paper the SAS drives may be specced at slightly longer MTBF.

7.2k drives should be fine, file servers are rarely IO intensive, and the 2GB cache will help anyway.

Any reason for RAID6? Unless you absolutely need the space then I would go for RAID10, purely from the reliability/simplicity point of view.

 

[nutcase]

I'd agree with sticking with SAS, even though in theory there should be no differences, on paper the SAS drives may be specced at slightly longer MTBF.

7.2k drives should be fine, file servers are rarely IO intensive, and the 2GB cache will help anyway.

Any reason for RAID6? Unless you absolutely need the space then I would go for RAID10, purely from the reliability/simplicity point of view.

This in all respects.

 

[Yaayuh!]

I'd agree with sticking with SAS, even though in theory there should be no differences, on paper the SAS drives may be specced at slightly longer MTBF.

7.2k drives should be fine, file servers are rarely IO intensive, and the 2GB cache will help anyway.

Any reason for RAID6? Unless you absolutely need the space then I would go for RAID10, purely from the reliability/simplicity point of view.

Cool, just really confirming my own thoughts.
Space, I need space, RAID10 just isn't feasible given the budget and cramming 2 more (2TB 2.5" Dell Near Line SAS 12Gb/s) drives in and I'll have hotspares too.

 

[nutcase]

Forget the hotspares, use them for R10 and just ensure the server is under decent warranty.

 

[Armageus]

Forget the hotspares, use them for R10 and just ensure the server is under decent warranty.

Disagree with that - one of the benefits of RAID10 is the relative simplicity / speed of rebuilds, having a hot spare there to rebuild to as soon as the controller detects anything slightly wrong, minimises the length of time your data is exposed.

By contrast, with RAID5 or 6, I wouldn't actually want hot-spares (although I would want cold spares), as I would want to choose when the rebuild takes place, to ensure 1) I had taken a full backup before rebuilding the failed drive (due to the extra stress placed on the array and risk of failure), and 2) to choose a period of lower activity e.g. outside of office hours, thus minimising array usage and impact on the rebuild.

 

[Caged]

Throw 10k, 15k SAS into the bin and use a flash tier.

 

[Yaayuh!]

Throw 10k, 15k SAS into the bin and use a flash tier.

Hahaha! if only!

 

[Caged]

Have you done the sums on SATA/NL-SAS and a TB or so of flash? 2TB NL-SAS disks in RAID6 is a combination of poor performance and high costs, except in the way you don't want.

If this is a Windows file server then I'd be tempted to swap the RAID controller out for an HBA and run Storage Spaces rather than limit yourself to a traditional RAID configuration.

 

[Yaayuh!]

Have you done the sums on SATA/NL-SAS and a TB or so of flash? 2TB NL-SAS disks in RAID6 is a combination of poor performance and high costs, except in the way you don't want.

If this is a Windows file server then I'd be tempted to swap the RAID controller out for an HBA and run Storage Spaces rather than limit yourself to a traditional RAID configuration.

Adding flash storage into a Dell PE server already with ProSupport and 12TB of storage just throws the budget unfortunately.

Funny you should mention HBA, I actually looking at that as an option at the moment. A 1U server option with HBA and a 12 drive JBOD box.

 

[Caged]

Dell are quite poor in terms of disk pricing. If you want a Windows file server then have a look at a NetApp E2800 connected via SAS to a PowerEdge.

 

[Liquidfox]

It'll be SAS regardless for its implementation, I won't drop to SATA.

But NL-SAS is essentially SATA anyway, you get all the downsides of SATA just with a SAS connector instead. We only use NL-SAS for backup targets, SAS everywhere else.