external esata enclosure for backup/replication

[vicmarto]

Hello guys.

Do you anticipate any problem about use one of these cheap 4 bays esata enclosures to backup/replicate the main zpool? These enclosures accept a "Single Mode" where the drives appears as individuals to FreeNAS, allowing to configure them as zraid or whatever.

The idea is to connect it by a single esata cable to a LSI SAS 9212-4i4e (already conveniently flashed)

If this solution is not recommended, please let me know of better alternatives please. Thanks!

 

[Arwen]

Part of the problem of using a 4 bay eSATA enclosure is that it uses a SATA Port Multiplier. Those tend to be poorly supported. It's possible your system may only see the first drive.

That said, if the 4 bay eSATA enclosure had 4 eSATA connectors, then it does not have a SATA Port Multiplier. In which case, simply use a 4 port SAS cable to 4 port eSATA connector.

The use case you describe is common one here. We don't have many good, tried solutions. Ideally we would want a selection of 1, 2 and 4 port bays, supporting both SAS & SATA.

My external bay ended up with a less than ideal internal RAID thing that I can disable. But it still ends up blocking SMART. Since I only use it for backups to 1 disk, it's not a problem, (yet).

 

[vicmarto]

Thanks Arwen for your help.

I see now that it's better to avoid SATA Port Multipliers. What about SAS enclosures? Something like this maybe?: https://www.newegg.com/istarusa-dag...re&cm_re=sas_enclosure-_-16-215-738-_-Product

 

[Arwen]

@vicmarto, Yes, that particular selection looks better. The SFF-8088 has 4 lanes, which uses 1 host disk port per 1 chassis disk port. So, no SATA Port Multiplier.

That same web store seems to have a slightly cheaper model with trayless design. Don't know if it meets your needs, but it also seems to use 1 SAS disk port per disk, so no SATA Port Multiplier.

https://www.newegg.com/p/1UW-0038-0...m_re=SAS_enclosure-_-9SIADZY6C90429-_-Product

You can still use SATA disks, just make sure the external cable is shorter than SAS standards permit. Something like 18 inches. When a SAS controller chip's disk port is used for a SATA disk, the electrical signalling levels and protocol changes to SATA. Thus, more limited cable length than a SAS disk would have.

 

[vicmarto]

Yeah, excellent explanation and suggestions. Really a big thank to you Arwen!

 

[droeders]

@vicmarto
That same web store seems to have a slightly cheaper model with trayless design. Don't know if it meets your needs, but it also seems to use 1 SAS disk port per disk, so no SATA Port Multiplier.

https://www.newegg.com/p/1UW-0038-00001?Description=SAS enclosure&cm_re=SAS_enclosure-_-9SIADZY6C90429-_-Product

I've been using this exact trayless version for almost 3 years (for offsite backup sets) and I've been very happy with it. Keeps the drives cool and haven't had any issues with data corruption, disk dropouts, etc.