On 01/07/13 at 04:24pm, Mike Cloaked wrote: > As part of my planning for setting up a home build computer which will use > two ssd drives - one a Crucial M4 mSATA drive (for root and boot > partitions) and a second larger Crucial M4 SATA III drive for the rest, I > have been reading up about partitioning and optimising such drives - > > It seems that it is important to partition with proper alignment to MiB > boundaries for partitions but I am unclear if this happens automatically or > not when setting up GPT partitions with gparted? ( I usually partition > using a liveusb running PartedMagic and then run gparted before installing > arch) > I am not user about gparted, but I know that gptfdisk handles this automatically as does fdisk these days. I am not so familiar with parted in general, so maybe someone else can step in here. > Also I have been seeing various bits of advice about ensuring that > excessive writes are avoided by using a non-default IO scheduler - with > "deadline" being the better option for SSDs than the default CFQ scheduler > - and it would seem that adding the parameter to the kernel line for boot > once a system is set up is perhaps a good way forward? How does that work > if UEFI booting? > I use a udev rule to determine what scheduler should be used for what. At one point I had both rotational disks and a solid state drive. So I continued to use CFQ for the rotational and I use NOOP for the flash based media. This is what I use: ACTION=="add", KERNEL=="sd[a-z]", ATTR{queue/rotational}=="0", \ ATTR{queue/scheduler}="noop" > In addition it is suggested that for a machine with a reasonable RAM (in my > case 8GiB) then reducing the "swappiness" parameter to 1 via systemctl, or > altering the relevant parameter under /proc/sys is the way to do it, even > if there is a swap partition on one of the SSDs. > If you have 8GB of RAM, you probably don't need swap. I have 8GB and don't use it. I have seen no ill effects, no OOM. But yes, if you have it, lower your swappiness and it will avoid writing to disk as much as it can. > I have also seen it suggested that TRIM support is important either > mounting with the "discard" option or running fstrim manually via a cron > job out of hours to avoid delays during writes whilst the system is in use. > > Finally I have seen suggested that the "noatime" flag be used for mounting > SSD drives. > I use noatime in general, as I don't really care about access times. It will still record times when you make changes to a file, so that is enough for me. Apparently, using noatime with mutt can mess mutt's functionality up. But this negative consequence can be minimized by using a Maildir if you use mutt. I personally use an anacron job to apply fstrim to my drives once a day. I find that is more than than enough. There are some drives that apparently are slowed down quite a bit when set to do trim on real time. I don't think that my drives are in this category, but I like being able to set the nice value of fstrim, so that is why I do it that way. > Can anyone on this list who has set up a recent SSD drive and has > experience of SSD wear issues, and levelling issues, offer any advice on > whether some or all of the above are important when using SSD drives in an > arch linux machine or whether partitioning and installing essentially with > defaults is going to lead to SSD problems, or not? > I don't think you need to worry about wearing out the drive. As long as you have a quality drive, which the Crucial M4s are, you should have no problems. > This will be my first foray into using SSD drives on any of my systems. > > Thanks for any replies. > > -- > mike c -- Sugar & Scruffy sugar.and.scruffy@xxxxxxxxx