Any reason for SAS over SATA in bulk storage (xxTB) HDDs

[KaneTW]

I'm building a new server, which will involve a NAS for slow/archival data. My current HDDs are a pair of 18TB Ultrastar HC550 SATA.

The new server will have a x16 backplane directly attached to a LSI 9400-16i HBA. The HBA will be passthrough'd to a ZFS VM, which will.. probably run RAID10 eventually.

Is there any reason to use the SAS version over the SATA version in this case? If it's SAS, I'll buy new 22TB HC570 drives and sell the 18TB ones or use them for backup. If SATA, I will keep using the 18TBs and add a few more.

 

[Wasmachineman_NL]

SAS drives are usually cheaper from what I gathered.

 

[KaneTW]

About the same (slightly more expensive) for new drives, and the used market for HDDs in Germany is terrible.

 

[Wasmachineman_NL]

About the same (slightly more expensive) for new drives, and the used market for HDDs in Germany is terrible.

The used market for HDDs in Europe in general is shit. I still haven't found any sanely priced >4TB HDDs.

 

[Breezy2428]

Suposedly there are advantages to SAS when you put many of them together, the drives, firmware & configuration are built for that environment, when you have a SAS backplane and the prices are similar SAS makes sense.

But if you already have the bulk of the drive space you need in SATA drives that's a bit tougher of a question.

 

[BackupProphet]

There is only one difference between SATA and SAS today, and that is cable length and stability. I have had many shit SATA cables, but very few issues with SAS cables. With this is mind, because of signal requirements of SAS, they also use slightly more power.
I would just go for whatever you find cheapest $ per TB.

 

[reasonsandreasons]

Native support for multipathing (multiple hosts, controllers, and/or cables connected to the same disks for failover) is a potential benefit, but if you have the appropriate interposers for SATA disks it isn't much of one. It also only really comes into play when you're dealing with disk shelves.

 

[BackupProphet]

There is no better performance, data integrity with SAS. SATA and hard drive vendors has cached up with SCSI. Data integrity features can be enabled and tuned in firmware, hdparm for SATA, sdparm for SAS. NCQ queue depth is plenty when were talking about spinning drives. There is a reason Google, Dropbox and so on run a massive amount of SATA. There is a difference between cheap consumer hard drives, and enterprise high quality hard drives that are commonly SAS. But the 18TB Ultrastar HC550 SATA is a enterprise grade hard drive. Another good summary is this thread https://www.reddit.com/r/DataHoarder/comments/di7y8z

 

[gea]

Main advantaged for SAS over Sata

- up to 2 x 24G instead 6G (better performance, HA/dual host possible)
- up to 10m cables instead 1m
- more robust and stable data transfers and expander usage
- full duplex instead half duplex

If you have the option, go SAS

 

[KaneTW]

I've already decided to continue with SATA and buy an additional 2 18TB SATA HC550s. Then I'll migrate the data off the existing 2 18TBs and turn it into a RAID10 ZFS pool.

One spec that changed is that I no longer use 16-bay direct attach but a 24-bay expander backplane (still effectively 16 bays as 8 bays will be used for (direct attach) NVMe)

SAS seems to be a very marginal choice for this overall, so I decided to not mix SATA/SAS in this pool and stay with SATA.

E: turns out it's not so marginal: there's a situation in which a failing SATA disk could bring the entire array down to a halt due to error handling differences, which is not acceptable. So SAS3 for the new disks and the old ones can be backup or something.

 

[nexox]

The main reason I use SAS is because they support proper error reporting through an expander, my experience with SATA is that you'll get an error up to the host system, but without any way to identify the disk that hit the error, which is kind of not what you want in an array.

 

[Whaaat]

The new server will have a x16 backplane directly attached to a LSI 9400-16i HBA

After switching from HBA330 to 430-8i HBA (LSI 9400-8i) I found that I can check SMART on SATA drive using vendor utility only (Seachest), ordinary GUI Windows tools no longer have access to drive's SMART. Weird because SAS drives work as before.

 

[louie1961]

I've already decided to continue with SATA and buy an additional 2 18TB SATA HC550s. Then I'll migrate the data off the existing 2 18TBs and turn it into a RAID10 ZFS pool.

Why raid 10 if it is "slow/archival" data? At most I might mirror it, but If its truly archival why even bother with raid at all? Seems like a waste of money, when what you likely really need for archival data is a good backup strategy (IMO).