What is SSD Caching and Should You Bother On Your NAS?

[Music] hello and welcome back and that's right as the title card says what is ssd and let's be more appropriate should you even bother ssd caching is one of those things that a lot of the brands are really shopping in your face recently aren't they they're just going oh my god we do ssd caching look at us we've got ssd caching bays everyone use ssd code why aren't you using ssd caching and a number of people that are just utilized the network attached storage device to get away from google drive dropbox and stuff like that i've gone whoa what is it because it's you know it's it's an understandable thing a lot of people get these ideas thrown at them or what they should do and youtubers like myself will just go oh my god this is so cool so let's talk about ssd caching let's talk about what it is let's talk about who uses it let's talk about whether you even need it what are the pros or other cons what are the types so let's get straight into it ssd caching has existed in one form or another for a long time it isn't just about network attached storage devices and servers indeed one form of caching ssd or not utilizing just memory will probably exist in the device that you are watching this on right now caching um in the form of network attached storage and data storage in general is applied with the idea that when you get a device like this and this has got hard drives inside of this have got four hard drives inside hard drives although they give you great capacity and generally apart from the last few days a few months of chia hard drives generally give you quite good value for money in terms of overall capacity now as good as all that sounds has to be said that hard drives these big mechanical discs things that when they're being operated and being read from on cylindrical discs aren't the quickest now another thing that came out in the last few years of course is ssds ssds have come along and blown everyone away they've existed for more than a decade and ultimately what they do is give tremendous performance but they give tremendous performance several times that you know three four five times out of hard drive sometimes they give you all of this performance but their overall capacity is much much smaller and their price tag is ever so much higher so there had to be a way to take advantage of both and that is how ssd caching came about i hate seagulls now ssd caching allows you to have a large array of hard drives all in together in a raid a big old storage pool and then a smaller area of ssds one or two or more combined together are then used in conjunction with them they're combined together running simultaneously you can take advantage of the faster access times on that on on data that lives on those ssds and there then the data that lives on the hard drives those slower hard drives there with a larger amount of space that can be accessed if and when you need it because if it's less less important in your home or business environment now a lot of people talk about ssd caching and ssd tiering like they are the same thing they are not very very different from one simple reason ssd tiering or tiered storage is when you have ssds i'll use this side is when you've got an area of hard drives such as these here and then you have an area of ssds like these and with tiered storage as data is being written to the device typically onto the hard drives the more frequently accessed data be it for video editing surveillance whether it's being used for os's whether it's being used for the general metadata those frequently accessed files are moved keyword there moved on to the ssds and next time when that data is required they are pulled from the faster ssds that's what tiering is but caching is different in its truest form when it comes to accessing data ssd caching is about having a copy of those files on the ssd not moving them a copy of them so a file exists in two locations not all the data just the most frequently accessed data and when you're interacting with the nas or any kind of server system really the more frequently accessed data that's been demanded the most will then be accessed from the ssd but again it exists on both of them that's the biggest difference between caching and tiered storage a little bit more to it that we're going to talk about in a moment but again don't get those two concepts mixed up now when it comes to caching ssd caching on a nas if you are going to consider utilizing and again later on at the end we'll talk a little bit more about who doesn't why when it comes to ssd caching it's worth remembering there are actually different kinds so the reason i've got these bits locked out here on the table is we've got the hard drives here we're going to put them there so you can see them we're going to use these ssds here these are the cache so again these hard drives would normally be in the bays off here and the ssds would be in the base of that doesn't have to be that way but more modern nas it kind of works that way and then you've got your client computer where you're using a laptop using a pc or there's multiple users in the environment so let's open this up we'll leave that there so when it comes to ssd caching the first most common and most affordable version of caching is known as read only caching it's also sometimes referred to as write around caching but read only caching they're very very similar concepts so say this laptop here is sending 10 gigabytes of data it's communicating them to the nas so again we'll ignore that now it's there these are the hard drives in that rate so it sends data but it doesn't touch the ssds it sends the data directly onto the hard drives it sends that data then maybe every day it's going to send more data but occasionally it's going to pull data from the ssds because it's going to keep asking for data from the nas where the hard drives are and as it notices the more frequently accessed data although sometimes it's going to be reading and writing from just the hard drives the minute the nas starts to realize that some of this data is the same date and over and over again it's going to do that thing where it puts a copy of it over here and therefore as this client machine is accessing the brand new data occasionally it wants the frequently accessed old data and then boom it will pull it from the ssd instead now the reason it's called read only cache is because the client systems cannot alter this data they don't have live access um they can't um edit it they've got the modification to it the only data that ever the only interaction this ever has is when data is sent to it from the hard drive there would also be periodic deletion as data falls out of favor so as the capacity starts to fill then it will get rid of the most um less frequently accessed data overall and it will get rid of it but it doesn't get rid of it completely all it does is get rid of the copy because the original file was still on your hard drives and read-only cache doesn't require any kind of parity or fallback or safety nets or whatever on the ssds because there's always two copies of the data there it's also the most affordable you can get away with just a single ssd it's the entry level ssd caching but it should be mentioned that it only really improves things one way and it still requires the system to learn what's the most important date that you're utilizing now next one up is right back ssd now this is a form of right caching a lot of people refer to this as right only caching as well but we're just going to stick with the the fact is right back caching now in this scenario when the client computer user is interacting with the nas the cache is incredibly important it lives there in the middle and the data is sent directly to the ssds it doesn't go straight to the hard drives and then as each block is completed it's then transferred over to the hard drives again when you are accessing the data from the client you are accessing the hard drives but it should be mentioned that when you are writing data you are writing to the ssds and then the system copies it over to the hard drive now i say copy it is moved because it will be destroyed it doesn't maintain a copy of the data there and in a lot of cases it is highly recommended that you have some form of parity so you have two drives in a raid configuration the reason being that during the right operation if something goes wrong or the system fails or the ssds break there's every possibility that because the hot data hasn't moved into your main storage area that has raid inside you'll lose that data so do bear that in mind right back or write only um caching is used but again it's mainly a right performance um improving endeavor and not as good in terms of business and archival data and regular operations as that of read-only or right around data and finally there is right through data now right through isn't just about nasa it's probably one of the most commonly used cache systems even though it's not generally referred to in this fashion now right through is often described in two different ways but they amount to the same thing either data is written from the client computer as it is uploaded to both storage systems simultaneously or data is passed through the ssd onto the storage media regardless of which way you put it it is them being data is being compiled onto them simultaneously whether it's every single time going through or sending them together now yes that is a dual operation that has to be said but remember you are then creating two lots of copy data onto them and when you are pulling data you can still pull data from the ssds it's not kept there long term it can't really because and remember ssd for ssd caching it'll be smaller amounts but right through caching is generally more utilized um across desktop systems and smaller pc computer systems for typical caching in terms of nas they don't really break down into all these individual read only right only type cash options they're out there and qnap is one of the brands out there that really do funnel them all down but in terms of reading and write caching a standard read write cache gives you the benefits of that last one then of course the read-only cache as well as you're accessing the data you are pulling the more frequently accessed data as well but also during the right operations you can see the cache data going nuts there on the cache management panel on all of those different nas devices but how much cash do you actually need in order to take advantage of it when it comes down to it just telling you you need the ssds isn't enough there's a lot of ssds out there and they're all varying interfaces and speed so first let's talk about the the amount that you're going to need so generally and there's no strict rule out there you can break it down mathematically but because of different hard drive raid arrays and capacity drives and the number of drives at all it can be very difficult to nail it down i personally will always utilize whatever my capacity limit is in terabytes i will have 10 of that value as ssd cash so for every 10 tb i want 1 tb of ssd cash bear in mind if you're going to take advantage of right based cash mechanics i generally would recommend that you have two ssds so again you can have to double up on that capacity so if you need one tb you need two one tvs to make sure you've got that raid support there um i mentioned interfaces there because it is of course worth highlighting not not all ssd caching in 2021 2022 is done with m2 nvmes a lot of it is done with traditional sata ssds that go inside the media base now a lot of people do query whether using nvme ssds is much better than using sata ssds for caching because despite the fact that sata ssds give you between five and 550 megabytes per second and nvme ssds can give you three to four thousand megabytes per second in pci agenda three times four can your nas actually take advantage of that additional speed in that caching and the answer is yes and no which really isn't helpful um when it comes to write activity and indeed read activity when you're interfacing between your laptop your computer your whatever and the nas the connection the interface between the nas and the client system will give you some idea about the maximum throughput of the data being sent through yes the internal performance of your system if you're using a cache where data is being moved between hard drives and ssds for overall system benefits yes the nvme is going to give you better performance overall i'm sorry nvme by a decent margin but externally you the end user the differences you're going to feel and responsiveness and latency are going to be very very small indeed especially if you're connected via 1gbe or even two three four um 1gbe connections um from your client system to the nas starter ssds they're already going to be maxed out at the right potential um of ssd caching with right caching onto those ssds in a point where nvmes when you utilize them just won't be plain enough they're just gonna be bottlenecked and you'll see no difference between them externally the true benefit of nvmes as ssd cache over sata ssds is in the internal operations and the databases that run within the system but even then it's not as cut and dry as that because a number of users will you know see a nas like this the ds920 that's got two nvme bays in so i can go cool score two um three times four gen ssds inside there these are knocking out something like three three and a half thousand megs each that's incredible however a lot of the nvme slots on a lot of modern nas devices aren't actually pcie gen 3x4 those m2 slots there the pcie lanes that are available and the chipset of the nas inside the cpu and the control and basically the general layout the groundwork of the nas system doesn't have enough pcie lanes available to give full bandwidth to each of those m2s inside and the ultimate end game there would be that if you put a three to four thousand megabytes per second ssd in those slots they will end up being bottlenecked to one or two thousand megs max anyway so although yes there are benefits to using nvme ssds for caching over sata ssds those benefits are all going to be internal that you're not going to see much of it externally unless you massively saturate those um you're able to saturate 10 gbe connections and higher and also is every possibility that unless you're using a particularly advanced xeon intel core or high-end amd processor that the m2 nvme slots on the nas you might be looking at if you're looking at celeron or even some of the real tech ones that support ssds there's every possibility that pcie lanes inside are already going to bottleneck those nvmes to to end with so who is ssd caching actually for should you utilize it is it even in your interest to adopt it well if you use databases of information for your business be it for website web images thumbnails indexes that sort of thing to run your site email services i've got lots of information being accessed shared drives between active users where it's a database of information of client information crm cms's you will benefit from nvme ssd cache insight or ssc cache you will you won't be able to measure it that much and the gains are made gradually over time as the system learns about the more frequently accessed files with more immediate benefits in right caching activity being visible but you will feel the benefits however if you're a multimedia user for plex media server or if you're just streaming over dlna if you're a photo video editor the you know the input output gains there are going to be very very small and barely noticeable and again you will be throttled by external network connections to a point where the nvme or sata ssd caching won't even be noticeable anyway sod caching is a great thing but it's not for everyone and i kind of wish brands would stop shouting in people's sodding face about ssd cash when i believe only around 20 percent maybe 25 a push percent of users who buy network attached droid servers rackman's desktop whatever will actually see the benefits but this has been what is ssd cache and do you even need it if you enjoyed this video click like if you want to learn more click subscribe if you are interested in getting the right network attached storage solution for you and need a bit of a helping hand use the free advice section over at nas compares it is genuinely free it's manned by two humans me and eddie the web guide and we're there to answer your queries we don't get paid because it's completely just impartial advice we'll give you we'll recommend a few stores but again shop where you like there's a donate button be great if you use it you don't have to and we don't keep your email it's as simple as that use it it's there where you lose thank you so much for watching and i shall see you next time

Channel: NASCompares

Views: 42,943

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Id: acForpcFHSg

Length: 17min 38sec (1058 seconds)

Published: Sun Aug 22 2021