From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: Running check and e2fsck simultaneously Date: Sun, 10 Nov 2013 21:43:13 -0600 Message-ID: <52805251.2010102@hardwarefreak.com> References: <527FCBAF.4070208@hardwarefreak.com> <58CD4AD8-0A1E-42E8-984D-F4727EE2B8F0@gmail.com> <527FDBC1.4000009@hardwarefreak.com> <527FE89A.4010608@hardwarefreak.com> <89667845-9A4C-4402-91BE-0817BCB02C6F@gmail.com> Reply-To: stan@hardwarefreak.com Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <89667845-9A4C-4402-91BE-0817BCB02C6F@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Ivan Lezhnjov IV Cc: "linux-raid@vger.kernel.org" List-Id: linux-raid.ids On 11/10/2013 5:08 PM, Ivan Lezhnjov IV wrote: >=20 > On Nov 10, 2013, at 10:12 PM, Stan Hoeppner = wrote: >=20 >> USB is not a storage protocol. USB devices often disconnect/reconne= ct >> for no apparent reason. We see this frequently with the little vend= or >> USB disk drives (Seagate/WD) and also generic disk enclosures. USB = is >> not a proper protocol for md/RAID storage. You may have continual >> problems with this setup. >> >> If the laptop has an eSATA port use eSATA. If not, drop in an eSATA >> PCMCIA card. This should be much more reliable than USB for this >> application. >=20 > Actually, it's a good piece of advice. Now all I need is to figure ou= t if I I can do this with the hardware I've got. >=20 > However, I feel compelled to say that my USB drives (I have had sever= al=85 4 to be precise, now 5) have been incredibly reliable throughout = all these years. No connection problems whatsoever, no flakiness/flappi= ng of any kind. Very solid and reliable as for a home, midrange 7 years= old laptop and three 7 years old drives. I've been using them for all = sorts of things, from backups to torrents and storing virtual machine d= isk images, etc. Very reliable. The only concern I have is that perform= ance sometimes may not be enough, but by and large it is not a problem = for me and so I get by just fine. >=20 > Installing an eSATA PCMCIA card is actually a great idea, and I almos= t falmpaced when I realized I could've probably resolved performance is= sues long time ago and the solution was in front of me all this time, b= ut then again the problem was from a pressing character and so I have b= een really content most of the time with what I have. >=20 >> >>>> Also, I see little/no value in running a scheduled mdadm check on = a >>>> RAID1 array. Any problems with RAID1 will be due to one of the di= sks >>>> beginning to fail in some mode, usually requiring sector relocatio= n. >>>> Most drives do this automatically until they run out of spare sect= ors, >>>> at which point md will throw write errors. Monitoring SMART data = and/or >>>> running SMART self analysis on a schedule is much more effective h= ere, >>>> as you will become aware of a problem sooner, and have the opportu= nity >>>> to correct it before it shows up in md. >>> >>> Bare with me, I know very little about how RAID works so I can some= times make totally absurd statements. That being said, I intend to moni= tor SMART values and I'm wondering now why does it make sense to run ch= eck on other types of RAID? I assume 5/6/10 mostly? >>> >>> I'm also wondering if it is advised to run check with filesystem mo= unted and in use, or unmounted? >> >> Instead of using a connection method known to cause problems with >> storage, and then attempting to mitigate such damage with array/fs >> checks after the fact, why not simply avoid the problem in the first >> place? Use eSATA, or build/buy a little NFS/Samba NAS filer. >> >=20 > As I said in my particular configuration it is a pretty solid connect= ion.=20 You've been lucky so far. I hope your luck holds. > No experience with NAS filers here, but I'm definitely looking this option up as well (already googled it up and reading a description). Network Attached Storage, A.K.A a dedicated file server "appliance". "NAS" is a catch-all term these days for a dedicated file serving device, whether NFS, Samba, Windows CIFS, etc. I mentioned this option because it gives you a dedicated storage server= , and decouples the sleep mode of your laptop from your bulk storage. There are DIY kits and full retail NAS boxen on the market that use ver= y little power. Here you would configure the drives to spin down, but no= t put the system into sleep, as the mainboard uses less than 10W anyway. > What about filesystem state? Does it matter if a filesystem is mounte= d when check is run? I'm not an EXT user. See "man e2fsck". With XFS you can check while mounted using "xfs_repair -n [device]", bu= t no repairs will be performed, you simply get a report. To repair a damaged XFS filesystem use the same command sans "-n" on the unmounted filesystem. xfs_repair will abort if the filesystem is mounted, and "-n" is not specified. xfs_repair is not to be automated via script/cron. It is only to be run if/when errors are encountered, usually after a crash, power loss, controller failure, etc. --=20 Stan -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html