tag:blogger.com,1999:blog-7913915168052873347.post617864455547656457..comments2024-03-26T13:00:25.188-07:00Comments on The Friedman Archives Blog: Backups, Kickstarter Ideas, and ReFSGary L. Friedmanhttp://www.blogger.com/profile/12816533617814819591noreply@blogger.comBlogger31125tag:blogger.com,1999:blog-7913915168052873347.post-32741281083041186262016-04-09T14:48:00.697-07:002016-04-09T14:48:00.697-07:00Hi Wing Tang Wong,
I did some research on your su...Hi Wing Tang Wong,<br /><br />I did some research on your suggestions. Using task scheduler in windows 10 requires some windows programming experience and I'm not at all sure a task can be setup to send a file from an external drive to a networked drive(s) or more to the point if I can figure out how to do it.<br /><br />Schedulecopy looks promising but it is in beta and only has 1 user review.<br /><br />The other program named watch 4 folder http://leelusoft.blogspot.in/2011/10/watch-4-folder-23.html looks promising but again I couldn't find any reviews other than on it's website.<br />GEGJrhttps://www.blogger.com/profile/17521332233522505394noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-61229295284975524972016-04-05T22:03:42.646-07:002016-04-05T22:03:42.646-07:00@GEGjr Cool. :) I've got Google Drive and Dro...@GEGjr Cool. :) I've got Google Drive and Dropbox as well. (Don't have OneDrive and don't use TeraCopy since I'm on the Mac).<br /><br />On the Mac, there is the built in TimeMachine, which will send backups to a TimeMachine capable device(TimeCapsule, MacOSX Server, USB drive, some NAS units). There is also the free software, Carbon Copy Cloner, which now has the means of scheduling automated copies from any SRC to any DST and even to multiple DST(s). Very very useful. <br /><br />On the Windows side of things(from googling), it looks like Windows has something called a Task Scheduler: http://windows.microsoft.com/en-US/windows/schedule-task#1TC=windows-7<br /><br />There looks to be a more customizable tool, ScheduledCopy, with multiple schedules and where you can specify SRC/DST individually: https://sourceforge.net/projects/scheduledcopy/<br /><br /><br />So, it's possible to set it up so that you schedule automatic copies of files to the location where your OneDrive/Dropbox will pick them up.<br /><br />Another option is a watched folder. So as soon as a file lands in the folder, its sent to where you want it to be sent. <br />Wing Tang Wonghttps://www.blogger.com/profile/15588459662357176465noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-40125125289394998292016-04-05T19:21:43.124-07:002016-04-05T19:21:43.124-07:00Sir, you are most welcomed. I would be remiss for ...Sir, you are most welcomed. I would be remiss for not mentioning that I got the best of the deal. You have urged me on to become more serious about my backup plan. I have USB drives and even have the NAS drive. What I'm missing and don't know how to setup is automatically doing the mirroring and the backup. For example, I keep my photos on a 2TB USB 3 drive, whenever I import from a card, I always do a simultaneous copy to my NAS which is partitioned into 2 drives. What I feel I'm missing is a way to make an automatic copy to a third location which will be stored at an off site location. Right now, I'm manually copying the first USB to Dropbox or OneDrive but only when I have time and think to do it and feel I've added enough new files to warrant the effort. I typically do the copy through Teracopy which even doing data checking it isn't slow but copying to OneDrive or Dropbox is not fast and I'm not comfortable starting the process and leaving the premises so I only do it when I know I'll be around a while.<br /><br />Fortunately, I am not shooting every day or even every week right now so there's no urgent need to do the backup. Although, I'd rather the copy be done to Dropbox or OneDrive every time I add even 1 image to my database.GEGJrhttps://www.blogger.com/profile/17521332233522505394noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-44238777800780939362016-04-05T13:57:48.387-07:002016-04-05T13:57:48.387-07:00I agree, it's not truly comparable to shopping...I agree, it's not truly comparable to shopping for most products/services.<br /><br />The thing is, proper backup is not a trivial thing. For companies, it represents being in compliance or not, at risk of losing actual monies or not. So enterprise grade backup solutions are in-depth types of solutions.<br /><br />My prior posts approaches things from that angle. Looking at solutions that mitigates most/all of the risk. Something that a small business on up would want to look into, but not necessarily DIY.<br /><br />It comes down to what level of protection you want, how much you want to spend, and how involved do you want to be with the backup process.<br /><br />I agree the comparison to shopping for products/services isn't a perfect fit. But many of the things you would do for a car, plumber, or insurance are similar. <br /><br />It comes down to determining what you want to protect, what you want it protected against, how much of it is there, how long you need to keep it around for, and how much you want to spend.<br /><br />I think what Gary originally posted re: 3 x USB3 drives, is a very workable solution. It's more labor intensive, but if your data set all fits, then it is very workable and very portable. <br /><br />The only thing I would do to augment it is to suggest using external drives that internally mirror between two drives. That way, you would be able to survive loss of a single drive.<br /><br />Like I said, my own setup at home isn't complete yet. ^_^;; I've got backups for my laptops, but not for my desktop. And certainly not for my larger archive.<br /><br />To back it up, I would need to build a second storage array capable of serving as backup to the first array. <br /><br />Btw, thanks for engaging me in this discussion. It's reminded me, I need to get off my butt and save up for that second array. <br /><br />You'll notice, though, that my setup is not unlike the one detailed by Gary. The only real material difference is that I'm using 8 drive arrays vs USB3 drive. :) Wing Tang Wonghttps://www.blogger.com/profile/15588459662357176465noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-47001359387687070752016-04-05T12:10:32.310-07:002016-04-05T12:10:32.310-07:00Wong, I certainly appreciate that like anything el...Wong, I certainly appreciate that like anything else a basic understanding is helpful. It's what I told my 87 year old mother about computers several years ago when I enrolled her in a basic computer class, it will be really helpful to her and me if she understand the difference in left and right clicking. Why didn't I teach her you might ask. Well, it's like teaching someone close to you to drive, not always a good idea if you want to keep harmony.<br /><br />That said and with all due respect for your obvious superior knowledge on the subject, I would hardly characterize understanding the complex world of an all encompassing backup strategy like "... car buying, insurance, babysitters, plumbers, etc. ". I can research a car without understanding why it runs, I can research a plumber simply by checking their past jobs or even easier by checking with Angie's List, etc, etc.GEGJrhttps://www.blogger.com/profile/17521332233522505394noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-58678780468238037162016-04-04T12:08:29.864-07:002016-04-04T12:08:29.864-07:00@GEGjr here is the answer to your second question:...@GEGjr here is the answer to your second question:<br /><br />But to your second question... quite honestly, building up a working understanding of what the terms mean and how things generally work will help you greatly in choosing a good service/product to make use of. It allows you to make an informed choice.<br /><br />But yes, you can rely on others. You can rely on hardware/software solutions. But even then, it's not just turn-on and use like a disk with USB connectivity. There is still some setup and there are still health indicators. The long and short of it is... even if you paid for professional consultants to design/build a multi-tiered storage array with local and remote backups for full disaster recovery, fault tolerance, and high availability... you would still need the expertise to use the system. The bigger and more complex the system is, the more maintenance it requires.<br /><br />Basically, at the end of the day... it's an investment. If your data is important to you, you would be well served to figure out the best way to protect that data. And to do that, requires having a working knowledge of the subject. <br /><br />It's the same with any other thing: car buying, insurance, babysitters, plumbers, etc. <br /><br />At the beginning, I felt that I didn't have time. That I would address the issue "later". The wakeup call was when my juggling act of several USB hard drives I used came tumbling down because it had been a couple of days since I rotated drives/copies, and one literally fell and hit the floor while it was running. Lost 2TB of data. It turns out my manual copying of data between drives had been lax. And it wasn't just 2 days of notes/emails/files/etc. I lost, but some random assortment of photoshoots, projects, and personal archives spread out over a 2 month period. Swiss cheese. And when I went to try to offload all the data from the remaining drives, I realized that while they worked fine most of the time, the moment I tried to do a full pull off of them, there were signs of bitrot from bad writes a long time ago that went undetected or because the enclosure was flaking out or a bad usb cable. <br /><br />At some point, the cost of losing data escalates to the point where it is worthwhile to make time to learn these things.<br /><br />I'm not saying everyone is going to lose data if they aren't fully read up on things and I'm not saying a single disk external drive is a bad idea. Just that all options have different levels of risk/cost/etc. <br /><br />There are certainly many more easy to use solutions out there today than there were some 8 years ago. You don't have to roll your own server. You can just go and pickup a beefy NAS unit with a good onboard controller, and you're set.<br /><br />It depends on your use case, your budget, and how much protection you want. But yeah, it really helps to invest the time to determine what you need for your situation. <br /><br />You don't need to be a specialist or a guru. Just need some baseline knowledge. Wing Tang Wonghttps://www.blogger.com/profile/15588459662357176465noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-44611504241472237932016-04-04T12:07:59.158-07:002016-04-04T12:07:59.158-07:00@GEGjr hmm... sorry, let me reclarify:
Given your...@GEGjr hmm... sorry, let me reclarify:<br /><br />Given your box/original data. The primary storage you have it on, if it is a single drive, like in most laptops/desktops, it is unprotected.<br /><br />If you store the data on an array and run your data off of that array, it is protected via the RAID. This protects you against single disk failures. The larger your disks and the larger your array, the more disk failures you will want to be able to survive, due to rebuild times. My 48TB raw/36TB usable RAID6 can suffer 2 disk failures. But the 6TB drives take 2-3 days to rebuild, from the time I replace the failed disk. If I were using RAID5, a second disk could fail in that timespan, causing complete data loss. So the bigger the disks and the larger the array, the more protection you will need.<br /><br />Low level errors can occur, which RAID may miss. So this can lead to bitrot. Which is why some advanced filesystems and some RAID servers will re-verify/refresh data on the array. This protects against bitrot. A write could have gone bad enroute to the disk. A head could have skipped a track due to vibration/shock. Brown out/power outage. etc. All of that can introduce byte sized, block sized, or even stripe sized chunks of errors, which if undetected and uncorrected, can result in corrupted data. Windows ReFS and Sun/Oracle's ZFS protects against this using checksums during each and every operation. RAID arrays protect against this by running checksum checks against the entire array periodically.<br /><br />So the above covers the different forms of primary storage. <br /><br /><br />So let's say you have your laptop and you backup to a TimeMachine. If that Time Machine is a physically separate set of storage from your laptop, then it is a backup. Ie, it isn't used as your primary storage. <br /><br />The same rules of data protection apply. Single disk = high risk. RAID5/6 = protection against disk failure. Checksums, either during operations or via periodic jobs = protection against bitrot.<br /><br />But let's say you have a desktop computer(or laptop) with an array attached to it all the time or most of the time. Even if you are storing your Time Machine backups to that array, because you are actively using the array as part of your primary storage, say you have an array that's split so you have 2TB for active data and 4TB for TimeMachine backups. If you lose the array, you lose your active data as well as your local TimeMachine backups. So generally speaking, one might not consider backups made to the array you actively use as a real backup.<br /><br />The issue being if a serious mistake is made, it can wipe out all data on the computer and all physically mounted storage. <br /><br />Same thing for backups of backups on the same array.<br /><br />If the array is connected ONLY for the sole purpose of making backups to, and is disconnected after backups are done, then that storage is considered a legitimate backup. If it has RAID and checksumming protections, then it is a backup protected against disk and bit-rot failure. <br /><br />My personal setup at home actually violates this definition of backup for my desktop, since I use the array as part of my primary storage. Though it is considered a legitimate backup for my laptops, which sends their time machine backups to the desktop's array via Apple's Mac OS X Server.<br /><br /><br />Storage arrays that offers "snapshots", ie, point in time "backups" of your data are basically local copies of your data(technically, copy-on-write deltas of your data, since there is only 1 copy, with differences written to other parts of the array). So loss of the array or loss of the main copy will risk loss of all copies on the array. It's like an "undo" vs a backup. Both ReFS and ZFS offer this feature as well. But neither considers this feature a "backup".<br /><br />The idea of backups is that you can go back to them in the event of a serious failure on your primary computer. If your backup is live storage on your primary computer, chances are, your backup will be impacted as well.<br />(answer to your 2nd question in another post)Wing Tang Wonghttps://www.blogger.com/profile/15588459662357176465noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-85665353043589391822016-04-04T03:24:26.580-07:002016-04-04T03:24:26.580-07:00Wing Tang, thanks for explaining the yet still con...Wing Tang, thanks for explaining the yet still confusing issues of backups vs syncing. I do somewhat get it but I must confess I still don't understand why creating a duplicate copy of a data set is not considered a backup? If I understand what you're saying an incremental backup or mirroring is NOT a backup even if it's data checked for errors?<br /><br />Why do I (we) have to be data processing or computer hardware and network specialist gurus to keep our data safe? Why can't I rely on the expertise of others so that if the box says backup it actually is backup? I think I might speak for a lot of people when I say I don't have the time or inclination to study data protection, reliability and longevity.GEGJrhttps://www.blogger.com/profile/17521332233522505394noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-42596589798571865342016-04-01T12:56:18.106-07:002016-04-01T12:56:18.106-07:00Wing Tang, everything you say is true. My attract...Wing Tang, everything you say is true. My attraction to ReFS was that it, too, proactively checked for bit rot without the need for a fancy RAID box with a proprietary file system.Gary L. Friedmanhttps://www.blogger.com/profile/12816533617814819591noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-77367092897325406672016-03-30T13:57:56.432-07:002016-03-30T13:57:56.432-07:00So answering one point before another.
Data check...So answering one point before another.<br /><br />Data checking or checksums: Boxes like Drobo or the awesome ARC-8050T2 do data checking periodically to ensure the data on the disks are valid. <br /><br />Invalid data can occur for any number of reasons: <br />* bad sectors on a drive.<br />* power loss or unclean restart/unplug/reboot<br /><br />The arrays are recalculating the checksums for blocks of data on the drives to ensure that the data is still correct.<br /><br />Note that RAID protection isn't backup. It's just data protection.<br /><br />And services that sync your data between your desktop/laptop to a remote device(USB drive or cloud service) needs to compare files to make sure all changed files are backed up and for the sake of efficiency, only transfer the changes. <br /><br />My ARC-8050T2 is configured to do a weekly re-checksum of all the disks' data to ensure nothing has gone wrong. <br /><br />Note, data can fade or become corrupted on drives for any number of reasons, the assumption with a RAID array like Drobo or ARC-8050T2 is that you want your data protected. And so it checks it periodically.Wing Tang Wonghttps://www.blogger.com/profile/15588459662357176465noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-24700745947549679232016-03-30T09:42:58.455-07:002016-03-30T09:42:58.455-07:00Anyone who proclaims ANY security scheme as being ...Anyone who proclaims ANY security scheme as being "unbreakable" is demonstrating their ignorance of the subject. SSL was designed to be strong and vastly preferable to unencrypted communication.Gary L. Friedmanhttps://www.blogger.com/profile/12816533617814819591noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-58334413642953916652016-03-30T08:58:05.909-07:002016-03-30T08:58:05.909-07:00My son whose IT company is hack attacked hundreds ...My son whose IT company is hack attacked hundreds of times a week responded to this idea saying that the hackers don't attempt to discover the key itself but use the technology that surrounds the key to break the system. He's opposed to any technology which allows any (including multiple) key access by third parties. As an example, SSL banking encryption was thought to be unbreakable.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-22796824671199859762016-03-13T14:06:41.850-07:002016-03-13T14:06:41.850-07:00I forgot to ask if you've tried using a progra...I forgot to ask if you've tried using a program named GoSync? It is a computer synchronization and backup program which allows for data integrity checks. I've been using it for a little while and although there's a bit of learning curve for non-backup geeks like me, if a person needs just simple backup or syncing it's simple to use. So far I've only used it to do data synchronization between external hard drives. I haven't tried using it to setup true backups from a connected external hard drive to a NAS device.<br /><br />I don't understand why raid systems say like Drobo have data checking? As you say what is the point of backing up an already corrupted file. I was always under assumption that once a file had been backed up that subsequent backups would check the same file for changes and verify the new file. I always had my backup program configured to only backup changed files.GEGJrhttps://www.blogger.com/profile/17521332233522505394noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-5931033982019722232016-03-13T14:05:17.681-07:002016-03-13T14:05:17.681-07:00Thanks for responding so quickly. I do remember re...Thanks for responding so quickly. I do remember reading those post. As a matter of fact I now use Teracopy. The only issue (always is) is I can't use Lightroom for direct importing. That means adding to a Lightroom catalog is now a 2 step process. The other thing is what about exporting edited or even unedited files from Lightroom or any other image management program? Programs like Lightroom don't have file integrity checkers do they? And I have noticed from time to time having issues when I tried to move or otherwise access some older files in Lightroom. I will get a message Lightroom couldn't open or move the file due to suspected corruption. I have a list of such files I haven't had time to investigate.<br /><br />Oh by the way have you are anyone you know ever used a program named Win-Hex to fix corrupt JPEGs?GEGJrhttps://www.blogger.com/profile/17521332233522505394noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-8613574880180578412016-03-11T16:12:07.453-08:002016-03-11T16:12:07.453-08:00Check out the links to two former blog posts embed...Check out the links to two former blog posts embedded in the first paragraph of this post. I talk about options there... Probably the easiest solution today would be to go for a NAS4FREE server and use that to hold all of your files.Gary L. Friedmanhttps://www.blogger.com/profile/12816533617814819591noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-11947606948030822812016-03-11T12:51:34.871-08:002016-03-11T12:51:34.871-08:00I always considered myself fairly knowledgeable, a...I always considered myself fairly knowledgeable, at least for a non-professional, about computers. But I had to look up ReFS. So is there anything for us non-pros to use that you pros would consider safe and dependable to keep our meager files save?GEGJrhttps://www.blogger.com/profile/17521332233522505394noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-38077060862043170152016-02-29T19:38:20.329-08:002016-02-29T19:38:20.329-08:00I would SO have bought that guitar, Gary!I would SO have bought that guitar, Gary!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-15122366473008300402016-02-23T12:06:27.674-08:002016-02-23T12:06:27.674-08:00After looking around, I may opt for a Synology sta...After looking around, I may opt for a Synology standalone NAS unit. They come with multiple gigabit ethernet ports and for backups, that would be more than fine. Wing Tang Wonghttps://www.blogger.com/profile/15588459662357176465noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-85168996938016876412016-02-23T11:07:23.030-08:002016-02-23T11:07:23.030-08:00Thanks for that reference; I had not heard of them...Thanks for that reference; I had not heard of them. (One red flag, though, is that there is no price list on their website...)Gary L. Friedmanhttps://www.blogger.com/profile/12816533617814819591noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-936541611928542202016-02-23T10:57:36.252-08:002016-02-23T10:57:36.252-08:00I don't trust them either... the basis of the ...I don't trust them either... the basis of the suggestion is that a warrant would have to be issued first. No balanced system is perfect, but this approach seemed reasonable to me. Regarding the extra code for validating credit card transactions, that sounds like a good start.Gary L. Friedmanhttps://www.blogger.com/profile/12816533617814819591noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-40716827569851484432016-02-23T10:25:11.384-08:002016-02-23T10:25:11.384-08:00Hi Gary, a message from Europe: your encryption so...Hi Gary, a message from Europe: your encryption solution seems to suggest that everyone in the world using Apple stuff should trust the American FBI as 'THE law enforcement' Well, I can tell you that I don't feel comfortable if Apple and FBI are the parties to decide whether or not to invade my privacy. Then on security of Credit Cards transactiosn : here we use an Credit Card Company App to generate a code for extra validation for credit card transactions...Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-65054935106121315662016-02-23T10:00:29.295-08:002016-02-23T10:00:29.295-08:00I'm a bit biased when it comes to the OS-based...I'm a bit biased when it comes to the OS-based solutions or software-raid setups. :(<br /><br />I agree that data needs to be protected at multiple levels:<br /><br />* physical hardware failures<br />* bitrot (signalling/software failures)<br />* OS crashes (kills software raid solutions)<br />* serious failures(malware/site damage)<br /><br />Bitrot protection like what ZFS and reFS do. (I think BTRFS supports a feature to detect/avoid bitrot as well)<br /><br />Mac OS X doesn't have a good approach to deal with this issue yet. I _could_ install OpenZFS on MacOSX, but the risk is that with any given OS upgrade, it could break. And that was a deal breaker for me. :(<br /><br />To date, my solution has been to go with a RAID6 array: ARC-8050T2 w/6TB disks. (48TB raw, 36TB Raid6 storage usable)<br /><br />The ARC-8050T2 has a scrub feature which can help to combat bitrot. I have it setup to scrub weekly. Not as tight a safety net as ZFS, but it's also not OS dependent. So upgrades to OSX won't impact the functionality of the ARC-8050T2's internal functions.<br /><br />The ARC-8050T2 array addresses bitrot and physical drive failures thanks to the built-in scrub/re-silver functions and the RAID6 configuration I'm using. Can suffer loss of any 2 disks. Which is good, because it takes about 2 days to re-silver a disk that has been replaced.<br /><br /><br />Time Machine backups from the desktop and laptops are sent to the array via the desktop(MacOSX Server). This provides a "backup" for the laptops and the desktop's OS/apps/user accounts. However, it does not provide a backup for the RAID array data itself.<br /><br />Original raw and hi res images are stored on the array, but the cache/catalog are stored on the system's SSD. <br /><br />Because it IS always-on storage and there is only one copy, it fails the backup test. But to do that, I would need another array to backup the data to. And that gets into the "*facepalm* I need to backup TB(s) of data..."<br /><br />The solution is to eventually create a second array of equal or greater size, which will be sync'd to nightly. Will probably use Bombich's Carbon Copy tool, which now has a scheduler function. So it can be setup to send the data to the second array periodically.<br /><br />I would probably setup the second array so that it is hosted off of a mac mini or something to keep it separate from the desktop.Wing Tang Wonghttps://www.blogger.com/profile/15588459662357176465noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-91605871148079095062016-02-23T08:45:53.941-08:002016-02-23T08:45:53.941-08:00Hi Gary. I simply use a blu-ray drive with M-discs...Hi Gary. I simply use a blu-ray drive with M-discs and put it in a safe away from home. Should be pretty safe (I hope)But I first had to have a HD failure to do that.:-(. I recovered most if not all, but hard work ... :-)Toonnoreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-417728685419893272016-02-23T07:45:59.604-08:002016-02-23T07:45:59.604-08:00Gary:
Re ebooks etc: take a look at eXtyles and th...Gary:<br />Re ebooks etc: take a look at eXtyles and the work of Bruce Rosenblum in Cambridge Mass. Or Inera.comAnonymoushttps://www.blogger.com/profile/13512447081298547799noreply@blogger.comtag:blogger.com,1999:blog-7913915168052873347.post-58856760557185808752016-02-23T07:44:05.873-08:002016-02-23T07:44:05.873-08:00Gary:
Re: ebooks etc. Take a look at exTyles and ...Gary:<br />Re: ebooks etc. Take a look at exTyles and Bruce Rosenblum, in Cambridge Mass.Anonymoushttps://www.blogger.com/profile/13512447081298547799noreply@blogger.com