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NFS 4.1 Support


Tin_Man_0
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I've been looking and looking to find an answer to NFS 4.1 on Synology. I figured this would be a good place to ask about possibilities. Synology has a great box and I like all the features, but some of them just don't really work all that well. Like iscsi. Good idea, good intentions, but slow as hell. NFS works like a champ, but I can't use mpio. I've found that Synology has NFS 4.0 support, but to get the multiple path options it has to be 4.1. Any way to patch this? it seems like such as small this. Just a 0.1 in version difference, but it's looking more and more that it's not that simple.

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patching DSM OS is not such a simple thing

while it's a linux distribution, it's not your typical linux distribution

everything needs to be compile from the grounds up to make it work with DSM.

 

and even if you manage to patch NFS 4 to 4.1 the new features you are looking for might not be usable from the user interface, you could always do it from the command line i guess.

 

that being said, if you want ISCSI to be fast, you'll need a faster network, something along the lines of 10 Gbps network card and fiber cables on both ends.

 

but if you are going to be spending that kind of money on a 10 Gbps network, might as well use the same money to slap in a proper RAID card + HDDs into the machine you want to use ISCSI, mainly because when ISCSI is enabled, it locks out a big chunk of the storage space just for the ISCSI file (which is the size of the HDD size you choosed to from OS side)

 

and depending on some implementations of ISCSI it might not be share-able concurrently with other machines.

 

it's not a true SAN, it's a fake ISCSI, all it does it creates a virtual drive inside a huge file like 500 GB or whatever size you choose your ISCSI device to be, when entering the size from the Control Panel.

 

I know WD, Qnap, Synology and most other NAS storage does it the same way, only true SAN servers that cost upwards of 10K can let you have true ISCSI which can be shared among multiple machines.

 

For the same reason, as you mentioned, I just stick with NFS and Samba shares, it works much better at any network speed.

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patching DSM OS is not such a simple thing

while it's a linux distribution, it's not your typical linux distribution

everything needs to be compile from the grounds up to make it work with DSM.

 

and even if you manage to patch NFS 4 to 4.1 the new features you are looking for might not be usable from the user interface, you could always do it from the command line i guess.

 

that being said, if you want ISCSI to be fast, you'll need a faster network, something along the lines of 10 Gbps network card and fiber cables on both ends.

 

but if you are going to be spending that kind of money on a 10 Gbps network, might as well use the same money to slap in a proper RAID card + HDDs into the machine you want to use ISCSI, mainly because when ISCSI is enabled, it locks out a big chunk of the storage space just for the ISCSI file (which is the size of the HDD size you choosed to from OS side)

 

and depending on some implementations of ISCSI it might not be share-able concurrently with other machines.

 

it's not a true SAN, it's a fake ISCSI, all it does it creates a virtual drive inside a huge file like 500 GB or whatever size you choose your ISCSI device to be, when entering the size from the Control Panel.

 

I know WD, Qnap, Synology and most other NAS storage does it the same way, only true SAN servers that cost upwards of 10K can let you have true ISCSI which can be shared among multiple machines.

 

For the same reason, as you mentioned, I just stick with NFS and Samba shares, it works much better at any network speed.

 

 

you are not quite 100% in your terms sir.

the iSCSI presented by WD/Qnap/Synology/Linux - is 100% TRUE iSCSI.

 

you are getting iscsi (a transportation layer (read: networking protocol)- allows the SCSI command to be sent end-to-end over local-area networks (LANs), wide-area networks (WANs) or the Internet)

with SAN (Storage Area Network)

 

the Virtual drive you are refering to is a LUN - which is how iscsi and FibreChannel work.

LUN : A logical unit number (LUN) is a unique identifier to designate an individual or collection of physical or virtual storage devices that execute input/output (I/O) commands with a host computer, as defined by the Small System Computer Interface (SCSI) standard

 

 

in more simpler terms - Iscsi is used for LUN access, and in this case we can say a LUN device is a block accessible device. (you are serving a full virtual drive for example)

NFS and SAMBA (CIFS) serve FILES. (the ride on the operating systems and Layer 7 networking, not layer 2 as isci)

 

Iscsi is inherently faster for systems designed to use it. because you are working DIRECTLY with block levels. no abstraction layers. where these lower end devices "FAIL" at is speed.

if you want faster Iscsi - you need faster drives with faster IO (raid10/SSDs/ETC) and you need to use it for the right reason; it's slow in file because it's not "really" designed for that. - you can 100% saturate a gigabit network with a "whitebox" SAN/NAS - remember - gigabit is slower than most sata3 Spinners.

 

there is more complete information i can provide; if this is questioned.

 

TL:DR - it's real iscsi - iscsi is for full drive sharing (block accessing, say VM images) - cifs/nfs is for files - iscsi (done for the right reason) will always be faster.

 

(yes, I am aware of file-based iscsi - I am not sure I know anyone who actually uses it. it's inherently slow (due to required overhead))

 

 

Sources : I am a network/storage engineer

 

EDIT - I have edited this a few times to clarify my hasty writing; forgive me for that.

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No worries, Thank you for the lecture.

 

I know I'm not expert in this subject, just the general perception of what it feels like when working with ISCSI with the NAS devices that's been available in the market, which as you can tell it has not been pretty due the poor speed performance compared to the regular NFS / CIFS layer.

 

I've seen complains of ISCSI as well even from people using 10 Gbps network, not just in this forum, but else where as well for other NAS devices.

 

It appears as you said, only authentic devices specifically created for iSCSI, can take advantage of iSCSI and provide the actual performance that it was supposed to offer, everything else feels like a poor-man's version of iSCSI

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No worries, Thank you for the lecture.

 

I know I'm not expert in this subject, just the general perception of what it feels like when working with ISCSI with the NAS devices that's been available in the market, which as you can tell it has not been pretty due the poor speed performance compared to the regular NFS / CIFS layer.

 

I've seen complains of ISCSI as well even from people using 10 Gbps network, not just in this forum, but else where as well for other NAS devices.

 

It appears as you said, only authentic devices specifically created for iSCSI, can take advantage of iSCSI and provide the actual performance that it was supposed to offer, everything else feels like a poor-man's version of iSCSI

 

I apology again if I went too far - i looked back and a few things can be better said;

I have not, but I can; look at what iscsi is doing on my ESXi DSM(5.2), and see what is required for good block access.

my setup will NOT be a good test case, I am using SHR - which in all aspects, is file level (or more correctly - quite a few layers to get to block level) - so iscsi will be hampered by that.

if DSM is using decent raid (raid-5 with write hole, ) then you should be able to get pretty decent speed.

 

looking at DSM's site :

https://www.synology.com/en-us/knowledgebase/DSM/help/DSM/StorageManager/iscsilun

looks like it explains it better than I did;

 

but then as you said "devices specifically created for iSCSI, can take advantage of iSCSI and provide the actual performance that it was supposed to offer, everything else feels like a poor-man's version of iSCSI"

we can do some tweaking, and some MPIO work - LUN packet sizes, proper raid; LUN allocation unit size (should match your type) but if you really want/need iscsi - DSM may not be for you.

for 99.999% of home labs, early mount NFS via fstabs (or other node supported ways) is going to get you what you need.

 

I do not mean to Lecture; there are things I learn every day myself.

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  • 1 month later...

Thanks for the feedback guys.

 

***But, after testing in real production and test labs I've found that iSCSI is no match for NFS when it comes to transfer rates. Even with MPIO or LACP setup iSCSI is simply no good for even multipile clients. I read what other people had experienced and they concur. Many of them flat out opted to create multiple NFS shares and assigning small groups of people per share in order to get the full glory of the performance of their Synology NAS, especially when they have chosen to add Read Write Cache, which if you look around every thinks it's a waste and that's only because the iSCSI performance really tops out at 500mb/s where as users who have NFS configured will get the full 1gb/s bandwidth per adapter. It's actually funny because when I setup MPIO for iSCSI on the synology, instead of at least getting 500mb/s on each adapter, it splits 500mb/s across all four meaning only 125/mbs each adapter. This is really unacceptable performance in my book. Especially since I have a Synology at home and I was really looking forward to trying to use it almost as a direct attach storage to my vmware server. I would love to get 4gb/s transfer rates to and from my Synology so I can use it as an elegant datastore and get the most out of my home server environment. I think that there's alot of people who just don't really say anything and just take it as it is, but I know better. The capacity is there for the synology to perform tremendously faster and be a serious competitor to direct attach storage devices like dell's Powervault MD series storage arrays.

 

*** All tests be they in a lab or in production were with VMWare 6.0+ and Synology DSM 6.0+

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